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Title: Growing rainfed corn and soybean after puddled flooded rice: I. Soil physical conditions and management (IRRI Saturday Seminar, November 4, 1978)
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Title: Growing rainfed corn and soybean after puddled flooded rice: I. Soil physical conditions and management (IRRI Saturday Seminar, November 4, 1978)
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Language: English
Creator: K., A. Syarifuddin
Zandstra, Hubert G.
Publication Date: 1978
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Subject: Farming   ( lcsh )
Agriculture   ( lcsh )
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Table of Contents
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Conclusion
        Page 12
        Page 13
    Reference
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
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Full Text








IRRI Saturday Seminar
November 4, 1978


GROWING RAINFED CORN AND SOYBEAN AFTER PUDDLED FLOODED RICE:
I. SOIL PHYSICAL CONDITIONS AND MANAGEMENT 1/

2
A. Syarifuddin K. and Hubert G. Zandstra-


INTRODUCTION


About two-thirds of the world's 137 million ha rice area is
rainfed (Barker and Herdt, 1978). As an example, Thailand's total
8 million ha of rice land, about 81% is rainfed (Chandrapanya and Banta,
1978). India, a country with the largest irrigated area in South and
Southeast Asia, has about 27% of her agricultural land irrigated (Framji
and Mahajan, 1969).

Presently, the rainfed as well as partially irrigated lands are
generally devoted to one puddled flooded rice crop (Chandrapanya and
Banta, 1978) though research and pilot extension programs do suggest that
growing two rice crops a year on this type of land maybe feasible (Zandstra
and Carangal, 1977). Because of the rainfall pattern, puddled flooded rice
is more suitable as a second rice crop in a double-rice cropping pattern
(Zandstra and Price, 1977).

As most of South and Southeast Asian farms are less than two ha
(Framji and Mahajan, 1969; IRRI, 1978), farmers find it difficult to make
a living with just one rice crop a year. Most of the land is left
uncropped until the following rainy season. To enable farmers to increase
their income, this seasonally idle land should be made more productive by
growing another crop after the last rice.

There must be some reasons why most farmers do not like to grow
upland crop after puddled-flooded rice. Therefore, the objectives of
this study were:

1. To study soil physical conditions after puddled-flooded rice
under rainfed condition and their effects on corn and soybean establishment
and performance.

2. To compare the effect of several cultural practices on soil
physical conditions and their effects on rainfed corn and soybean establishment
and performance.



1/
Part of the first author's Ph.D. Thesis submitted to UP at Los Baftos,
Philippines.
2/
Research Fellow and Head, Multiple Cropping Department, IRRI, Los Bafos,
Laguna, Philippines, respectively.












Soil physical conditions of puddled-flooded rice

In order to obtain a proper puddling for the rice crop the soil
needs to be above saturation (Sanchez, 1976). If there is insufficient
moisture, puddling is incomplete. As a result there are more weeds, rice
growth is poor and thus, the yield is low (Sanchez, 1976). Puddling is
needed to ease rice transplanting (Duff and Bandyopadhyay, 1966), reduce
percolation rates (Sanchez, 1976) and for more efficient fertilizer use
(Sanchez and Bradfield, 1970). Flooding insures sustained soil moisture
for rice (Sanchez, 1976), increases availability of most soil nutrients
(Ponnamperuma, 1977), suppresses weed growth and thus, increases rice
yield (De Datta et al, 1970).

On the other hand, puddling breaks down soil aggregates into particles,
increases soil bulk density upon settling which then becomes compact and
hard upon drying (Sanchez, 1976). Flooding expels most 02 from the soil
and the residual is soon exhausted by the soil microorganisms (Dudal, 1968;
Ponnamperuma, 1972; Patrick and Reddy, 1977). Except for the surface layer,
the whole plow layer remains reduced when flooded (Koenigs, 1950) and for
a considerable time after drainage (Sanchez, 1976; Melhuish et.al., 1976).
These conditions are unfavorable for growing upland crops, particularly
after rainfed rice where there is greater risk of drought.

Yields of soybean grown after puddled-flooded rice were lower than
that after unpuddled non-flooded rice (Floresca, 1968). It was also
found that the Fe-content of the soybean leaves grown after puddled-flooded
rice was 2-3 times higher than those grown after unpuddled non-flooded rice.
Palada et.al. (1976) reported the yields of several upland crops grown
after puddled-flooded rice in Iloilo, Philippines. Mungbean yielded from
200 to 750 kg/ha and from 1110 to 1850 kg/ha under low and high tillage
treatments, respectively. Cowpea yielded 30 to 120 kg/ha and 550 and
1050 kg/ha under low and high tillage treatments, respectively. Corn yielded
2.1 to 2.9 t/ha under high tillage.


Methods and management

Six fields and one greenhouse experiments were conducted at the
New Lowland Farm and at the Plant Physiology greenhouse of IRRI, on a Lipa
clay loam soil. The soil texture was lighter at depth with a pH of
about 6.2, organic C 1.5% and most of the available nutrients were within
normal range. When unpuddled, the top 0-20 cm had 25.4 and 45.7%7/ moisture
at permanent wilting point and field capacity, respectively. When puddled,
the moisture contents were 26.8 and 48.5%, respectively. Weather during
the course of these experiments is shown in Figure 1 and Table 1.

Experiment 1. Corn was grown after rice in three main plots --
unpuddled non-flooded, unpuddled-flooded and puddled-flooded--. The corn
seeds were dibbled into no tillage, row tillage (soil within 20 cm width
100 cm apart was rotovated twice) and complete tillage (thorough rotovation

1/Soil moisture content is expressed on an oven dry weight basis,
unless otherwise specified.












twice) as the three subplots. One sub-subplot was without and the other
with fertilizer (0-0-0 vs 60-60-60). This split-split plot experiment
had three replications.

Experiment 2. Corn was dibbled into a soil that had been intensively-
tilled to about 20 cm depth. The plots were plowed twice then rotovated
thrice after puddled-flooded rice. The corn had four different fertilizer
rates: 0-60-60, 60-60-60, 120-0-60 and 120-60-60. The fertilizers were
placed either shallow -- about 5 cm depth -- or deep -- about 20 cm
depth --. The corn was grown either with or without mulch 1/. The four
fertilizer rates, two fertilizer placements and two mulching treatments
formed a 4 x 2 x 2 factorial randomized complete block experiment with
three replications.

Experiment 3. The puddled-flooded rice field was drained at three
different times at 21, 11 and 1 day before rice harvest (DBRH). After the
rice harvest soybean seeds were dibbled into five different tillage treatments --
no tillage, furrow tillage, bed tillage, one rotovation and three rotovations --
(Figure 2). The three drainage and five tillage treatments formed a 3 x 5
split-plot experiment with three replications.

Experiment 4. Soaked (24 hours) and unsoaked soybean seeds were
either broadcast or drilled into the rice field at two DBRH with two seeding
rates of 60 and 120 kg/ha. They form a 2 x 2 x 2 factorial randomized
complete block experiment with four replications. In this particular experiment
the rice straw of each plot was cut after panicle harvest and left in the plots
as mulch for the soybean.

Experiment 5. To support the two previous soybean experiments,
Experiments 3 and 4, a greenhouse experiment was conducted using half-drum
pots. Four hills of transplanted rice were planted in each pot. The soil
was puddled to about 20 cm depth. Sixty-three seeds (97 % germination)
of 21 hills were either laid on the surface or dibbled to 3 cm depth at
two DBRH. The four different times -- 9, 6, 3 and 0 days -- to drain the
rice pots before soybean planting and the two planting methods composed a
2 x 4 factorial randomized complete block with three replications.

Experiment 6. This experiment was conducted based on the results
from Experiments 3, 4 and 5. Four different planting methods -- drilled
relay, no tillage-sequential, furrow tillage-sequential and one-rotovation-
sequential -- in combination with or without mulch, composed a 4 x 2 factorial
randomized complete block experiment with four replications.

Experiment 7. This experiment consisted of 10 planting times of no
tillage soybean, from 0 to 18 days after rice harvest (DARH) with an interval
of two days. The 10 planting times were combined with two rice straw
treatments. Straw was cut and removed during harvest or at each soybean
planting time. This 10 x 2 factorial randomized complete block experiment
had three replications.


1 The mulch rate was 8 ton rice straw/ha (about 50% moisture content).












The rice fields of Experiments 1, 2, 4 and 6 were drained at 11 DBRH,
while Experiment 7 at one DBRH. Rice (IR26) was fertilized with 90-60-60
rate while soybean was fertilized with 30-60-60 as band placement at planting
except for broadcast seeding treatments of Experiment 4. Soybean, TK-5,
was used in Experiments 3, 4 and 5 and Clark-63 was used in Experiments 6
and 7. Corn, Penjalinan, an 80-day variety from Indonesia, was planted at
150,000 plants/ha, then thinned to 50,000 plants/ha at 30 days after
seeding (DAS). The corn was fertilized with 60-60-60.


Climate

The rainfall for upland crops was below average (Table 1 and Figure 1).
During 1966-1976 rainfall was less than 40% below that received during the
experimental period. Looking at the December rainfall, only two of the
eleven years had extremely low rainfall experienced during the experiments.
The usual high rainfall in December may cause poor crop establishment.
However, this high December rainfall is usually less during the later part
of the month. Therefore, the later part of the month is suitable for growing
upland crops.

Both rainfall for the upland crop and the 1966-1976 average, except
for December, were well below the moisture loss from pan evaporation.
Although the moisture loss from dry soils is smaller than from pan evaporation,
it is obvious that there was water shortage.


Soil water table

The water table in the experimental area was shallow varying from
15-30 cm in the rainy season to 54-66 cm in the dry season. The actual
water table in the farm area was deeper than in the experimental area,
this being surrounded by other puddled-flooded rice fields. As the texture
of the 40-60 cm layer is coarser than the top layer, water could easily
move from the adjacent flooded fields to the non-flooded fields; hence,
the shallow water table in the non-flooded fields. This shallow water
table was the reason for the high soil moisture in the 30-60 cm layer even
during the dry season. The soil moisture in this layer never reached the
permanent wilting point.


Soil moisture

Rate of soil moisture loss. In spite of the high water table,
soil moisture in the 0-30 cm layer varied significantly as rainfall
decreased, because of different treatments imposed on the soil, though this
difference declined with depth. Experiment 7 -- puddled-flooded rice soil
on no tillage where the field was drained at one DBRH -- showed a negative
linear relationship between soil moisture content (in mm) and the square
root of number of DARH. The relationship for 0-18 DARH in the 0-5 cm
layer was:












Y 47.14 7.52 X1 R2 0.996** (1)

and in the 5-10 cm layer:


Y : 43.14 5.14 R2 0.971* (2)


The rate of moisture loss from the 0-5 cm layer was higher than
that of Adelanto clay loam, which was 5.08 as reported by Ritchie (1972).
This difference could be due to different percolation rates and stage of
observation. At the beginning of Ritchie's experiment the soil was at
field capacity, while this study started with soil above saturation
(about 807). Another possible factor could be soil cracking, which is
more intensive on puddled soil than unpuddled soil. Cracking increases
evaporation and percolation rates. The rate of moisture loss from the 5-10
cm layer was less than that from the top 0-5 cm.

Effect of drainage prior to rice harvest on soil moisture content.
The greenhouse experiment (Experiment 5) showed a significant effect of
time at which rice pots were drained prior to harvest on soil moisture
content after rice harvest within respective time and depth of sampling
(Table 2). The effect of time at which the rice pots were drained was
less granounced at depth. The differences due to different times of
drainage at 15 DAS were smaller than those at seeding. This means that
the higher the moisture content, the greater the rate of moisture loss.

The field experiment (Experiment 3) also showed a significant effect
of time of drainage prior to rice harvest on soil moisture content after
rice harvest (Figures 3, 4, and 5). The trend was similar to that in the
greenhouse. The difference was smaller with thedeeper and later samplings,
for example, the effect of time of drainage on soil moisture content in
the 5-15 cm layer at 60 DAS of soybean grown after rice, was no longer
significant. Because initial drainage is rapid, but tapers off with time,
water loss from fields drained between 21 and 11 DBRH was fairly similar,
but fields drained between 11 and 1 DBRH differed substantially in water
contents. Therefore the effect of the time at which fields were drained
on soil moisture content after rice harvest was smaller before 11 DBRH
than afterward.

The soil moisture content under soybeans at 40 DAS in the 0-5 cm
layer was below the permanent wilting point and in the 5-15 cm layer,
it was close to the permanent wilting point. At 60 DAS, the moisture
content in the 5-15 cm layer was very near the permanent wilting point.
Soil moisture in the 0-5 cm layer is important for crop establishment, while
the content within the 5-15 cm layer is important for crop growth.

Effect of tillage on soil moisture content. Experiments 1, 3 and
6 showed that soil moisture within the 0-5, 5-15 and 15-30 cm layers at
planting decreased with increasing tillage intensity (Figures 3, 4, 5, 6











7; Tables 3 and 4). The effect of tillage on soil moisture content also
decreased with depth as with the drainage treatments. Aside from the effect
of tillage per se, delayed tillage also significantly decreased soil
moisture as shown by the relationship in Equations (1) and (2). Tillage
was delayed to attain suitable soil moisture for proper land preparation.
The effect of delaying tillage resulted in a longer turnaround period on
rotovated treatments (Tables 5 and 6).

The soil moisture content under furrow tillage was always higher
than that under other tillage treatments (Figures 3, 4, and 5). The
bottom of the furrows was about 10 cm below the original soil surface.
Hence, the 0-5 cm and 5-15 cm layers under this tillage were actually
10-15 and 15-25 cm below the original surface, respectively (Figure 2).
As the soil moisture content increased with depth, the furrow tillage
resulted in samples with higher soil moisture contents than no tillage
for similar sampling depth.

Bed tillage led to a greater evaporative surface than no tillage
(Figure 2). Therefore, the rate of moisture loss from bed tillage plots
was higher than from no tillage. At planting, the soil from bed tillage
and no tillage had similar moisture contents (Figure 3). However, at
later sampling times the soil moisture content under bed tillage was
lower than those under no tillage (Figures 4 and 5).

Within the 0-5 cm layer, the relatively dry soil under rotovated
tillage acted as a mulch for the lower layer. The mulching effect of this
layer was indicated by the relatively higher moisture content with
the 5-15 cm layer under rotovated plots than those under no tillage plots
at 40 DAS (Figure 4). The soil moisture content in the 5-15 cm layer under
three rotovations was slightly higher than those under one rotovation.
This means that the mulching effect of the dry top layer can be intensified
by a more pulverized soil structure.

The effect of tillage on soil moisture content was not any more
important at 60 DAS because the strong dry season had reduced all moisture
contents to extremely low levels (Figure 5).

Effect of mulching on soil moisture content. Mulching was effective
in reducing the evaporation loss of soil moisture. The moisture contents
of mulched plots were significantly higher than those of unmulched plots
(Figures 6 and 7; Table 7). The effect of mulch also decreased with depth
since the soil moisture content within the lower layers remained high.
However, the effect of mulch could still be observed in the 15-30 cm layer.

The effect of mulch was small at the beginning of the upland crop
period. It increased during the middle and then decreased again at the
end of the period (Figures 6 and 7). This could be attributed to a
relatively high soil moisture content at the early stage, when the unmulched
plots also had sufficiently high soil moisture. As the soil dried, the rate
of moisture loss from mulched plots was smaller than those from unmulched
plots, which resulted in higher differences between mulched plots and














unmulched plots. At a later stage, moisture from both mulched and unmulched
plots was exhausted so that the rate of moisture loss and the difference
between treatments declined.

Effect of rice growing systems on soil moisture content.
Experiment 1 showed that the soil moisture content under corn after
puddled-flooded rice was higher than that after unpuddled-flooded. After
unpuddled-flooded rice soil moisture content was higher than after unpuddled
nonflooded (Table 3). These differences decreased as the soil became
drier, and at 50 DAS the differences were no longer significant (Table 4).


Soil impedence

Soil impedence in this study was indicated by the resistance produced
by soil to a cone penetrometer, expressed in kg/sq cm. The minimum resistance
that could be measured by the cone penetrometer was 0.8 kg/sq cm. This value
was obtained near the top of the no-tillage surface of puddled-flooded rice
at about 40% soil moisture content and at 10 cm depth at about 70% soil
moisture content (Table 8). This table together with Figure 8 show that
the lower layers of the soil were more compacted than those at the top.
This led to different relationships of soil moisture content and resistance
between these two layers. Experiment 7 showed a negative linear relationship
between soil resistance at surface -- 0 cm, (Y) -- and soil moisture content
in the 0-5 cm layer, (X):


Y = 13.99 0.31X R2 = 0.97 ** (3)

for X ranges from 42 to 28% (ODW). For soil resistance at 10 cm depth (Y)
and soil moisture content in the 5-15 cm layer (X) a negative exponential
relationship was preferred.

2
Y = 18.40-0.34X R2 0.98** (4)

for X ranges from 49 to 40% (ODW).

Tillage is one method to reduce soil compaction. Figure 9 shows
that for the same soil moisture content the resistance of tilled plots at
5 and 10 cm was smaller than those of no tillage. However, at the same
time, tillage also reduced soil moisture content. Therefore, the resistance
of tilled plots under corn after puddled-flooded rice was higher than for
no-tillage plots (Figure 10). The soil resistance remained low under
mulching (Figure 9).

Figure 11 and Table 9 show that the soil of puddled flooded rice was
more compact than that of unpuddled rice. There were no significant
differences in soil resistance between the two unpuddled rice types (flooded
and non-flooded).












Crop establishment.

a. Relationship between soil moisture content and crop establishment.

Non-dibbled planting on no-tillage plot. The greenhouse experiment
(Table 10) showed that the higher the soil moisture content with the 0-5 cm
layer, the higher the percent soybean establishment was for surface placed
seeds. This relationship showed the need for sufficient and sustained
moisture to establish a germinating seed. Therefore, to ensure good crop
establishment after non-dibbled planting, the rice field should not be
drained too early. Further study to determine the proper time to drain
the rice field for obtaining the best crop establishment under the broadcast
or drill method is needed. The rice field of Experiment 4 was drained at
11 DBRH or 9 days before soybean seeding (DBSS). Table 11 shows that by
soaking the soybean seeds for 24 hours prior to seeding, the percentage
of plants established increased by 23%. If the rice field was drained
close to the seeding time, the soaking might not increase the stand because
the soil moisture would be high enough (Equations 1 and 2) to obtain a
high crop stand.

Dibbled planting on no-tillage plot. The same greenhouse experiment
(Table 10) and Experiment 7(Figure 12) showed that if soybean seeds were
dibbled into 3 cm soil, the percentage of crop establishment was low at
the very high soil moisture content in the 0-5 cm layer. The percentage
increased as the soil moisture decreased until an optimum at moisture
contents of 50-56%, where the highest percentage of established plants
was achieved. It then decreased as the soil moisture content further
decreased. This study showed that the relationship between the percentage
of crop establishment (Y) and soil moisture content (X) before the peak was:


Y = 10.73 + 1.59X R2 0.92** (5)

for X ranging from 90 to 48% (ODW). The relationship after the peak was:


Y 163.02 1.33X R2 = 0.98** (6)

for X ranging from 56 to 28% (ODW).

b. Effect of tillage on crop establishment.

Tillage, through its effect on soil moisture content and sustention,
indirectly affects crop establishment.

Furrow tillage had lower crop stand than no tillage (Tables 12 and
13). As shown earlier (Figure 3), furrow tillage at planting had higher
soil moisture content in the 0-5 cm layer than no tillage. The excess
soil moisture decreased 09 supply for seed germination (Equation 5). The
seed was placed at about 10 cm below the original soil surface. This layer
was intensively reduced during the puddled-flooded rice-growing season.













Bed tillage and one rotovation had crop stands comparable to no
tillage. However, with three rotovations the crop stands was about 50%
of the no-tillage stand, and soil impedence was greatly reduced. The
excessively low impedence and low soil moisture content caused poor crop
establishment. All the seeds swelled but many of them stopped growing or
were killed by fungi.

c. Effect of mulching on crop establishment.

Like tillage, mulching through its effect on soil moisture content,
also affected crop establishment. Table 13 shows that the number of plants
was slightly higher in mulched plots than in unmulched plots, except for
furrow-tillage plot, which was reversed. Mulching and seeding were done
on the same day. The soil moisture content of unmulched plots was still
high at this time, except in rotovated plots. Because of reduced moisture
loss, the soil moisture content of mulched plots was slightly higher than
that of unmulched plots during germination (Figure 6).

d. Effect of rice growing systems on crop establishment

Rice growing systems, through their effects on soil moisture content
and soil impedance, indirectly affected crop establishment. Figure 13
shows that the corn stand after puddled-flooded rice for the same soil
moisture content was lower than that after unpuddled-flooded rice. That
after unpuddled-flooded rice was slightly lower than that after unpuddled
non-flooded rice. For the same soil moisture content also, the resistance
to cone penetrometer of soil after puddled-flooded rice was higher'.han that
after unpuddled flooded and after unpuddled flooded was slightly higher
than after unpuddled non-flooded rice. Therefore, soil impedance affected
crop establishment. A compact puddled-flooded soil has less macropores
and more micropores than a granulated-unpuddled soil. Therefore, for the
same soil moisture content, a compact soil has less available moisture than
a granulated soil, it also has lower water conductivity than a granulated
soil.


Crop performance

a. Relationship between soil moisture content and dry matter production

Non-dibbled planting. Table 14 shows a decreasing dry matter weight
per plant as soil moisture in the 0-5 cm and 5-15 cm layers decreased.
Therefore,it is not necessary to drain the rice field too early if growing a
broadcasted or drilled relay planting soybean after rice is preferred.

Dibbled planting. Figure 14 shows a quadratic relationship between
soil moisture content within 5-15 cm at planting (X) and dry matter production
of soybean per plant (Y):


Y = 15.56 + 0.70X 0.006X2 R2 = 0.97**












for X ranging from 37 to 63% (ODW). The relationship showed that the optimum
soil moisture content at planting in the 5-15 cm layer for dry matter
production per plant was 58%. The greenhouse data showed a similar value
(Table 14 vs. Table 2).

The soil moisture content within 5-15 cm at planting also showed
a quadratic relationship with dry matter production per sq meter (Figure
14) as:


Y = -484.12 + 22.16X 0.18X2 R2 = 0.74** (8)

for X ranging from 37 to 91% (ODW). This equation has a slightly higher
optimum value of 62% than Equation (7).

As a result of the high soil moisture content, there was poor root
development due to poor aeration. Therefore, plant growth was stunted and
dry matter was low. On the other hand, less dry matter, mainly due to soil
moisture shortage, would result if the soil moisture content was lower than
optimum.

b.- Effect of soil impedence on crop performance.

It is difficult to separate the effect of soil impedence from that of
soil moisture on crop performance, because soil moisture and soil impedance
are strongly related to each other as shown by Equations (3) and (4).
However, looking at the dry matter produced by corn grown after different
rice growing systems, the soil impedance also affected corn dry matter
production. Although the soil moisture content of fertilized plots at
planting after puddled-flooded rice was higher than those after unpuddled-
flooded rice (Table 6), the dry matter produced after puddled-flooded was
less than those after unpuddled-flooded rice (Figure 16). The soil impedence
after puddled-flooded rice was also higher than those after unpuddled rice.
Therefore, the low dry matter produced after puddled-flooded rice was partly
due to high soil impedance. Soil compaction also had effects on crop
establishment for the same reason, that given the same soil moisture content,
a compact soil has less moisture available for germination and early growth
than a non-compact soil.

c. Effect of tillage on crop performance

Furrow tillage at planting had moisture contents in the 5-15 cm layer
at 57, 58 and 64% (Figure 3) and 54% (Figure 7). According to Equation (8),
the dry matter production should be 194, 196, 197 and 189 g/sq m, respectively.
However, data from Tables 15 and 16 showed that dry matter production by
this treatment was lower than the estimated values. The lower dry matter
production under furrow tillage was related to some nutrient imbalance of the
soybean crop. A detailed report on this aspect is discussed in the other
part of this study.

Bed tillage produced less dry matter than no tillage, mainly due to
a lower soil moisture content, particularly during the rapid growing stage.













Rotovated plots at the flowering and pod-filling stages had higher
soil moisture content in the 5-15 cm layer than no tillage. Rotovated
plots also had lower soil impedance than no tillage (Figure 9), resulting
in good soil moisture content as well as aeration for soybean growth.
Individual soybean plants and corn plants under rotovated plots also performed
better than under no tillage (Figure 12). The dry matter production per
sq meter of soybean from one rotovated plots was slightly higher than those
of no tillage, although the crop stand was slightly lower. The plots rotovated
thrice produced the best individual plant performance among the different
tillage treatments (Figure 16).

In spite of its low crop stand, which was only about 50% of no tillage,
the dry matter per sq. meter was only slightly lower than that of no tillage
treatments (Table 15).

d. Effect of mulch on crop performance

Mulch significantly improved crop performance (Table 16). It
effectively reduced water evaporation loss, which resulted in a high moisture
content and low soil impedence -- conditions favorable for plant growth --
as compared to unmulched plots (Table 8; Figures 6, 7 and 9).

e. Effect of rice growing systems on crop performance

Figure 17 shows that dry matter produced by corn grown after
puddled-flooded rice was lower than when grown after unpuddled-flooded rice,
while dry matter yields after unpuddled flooded and unpuddled non-flooded
rice were similar. The inferior dry matter production after puddled-flooded
rice could be attributed .to the high soil moisture content and soil impedence
and low nutrient uptake, while after unpuddled non-flooded rice low yields
were mainly due to low nutrient availability. Aspects related to nutrient
uptake are discussed in another report of this study.


Crop yield

In this study, it was found that there was a good linear relationship
between dry matter production and yield for both corn and soybean. The
relationship of corn grain yield in kg/ha (Y) and total dry matter weight in
g/sq m (X) is presented as:


2
Y = -512.90 + 6.04X R = 0.95** (9)

for X ranging from 48 to 500 g/sq m; and for soybean:

Y = -45.38 + 8.15X R2 0.90** (10)

for X ranging from 63 to 183 g/sq m. Therefore, any factor affecting dry
matter production as described earlier, also affected corn and soybean
yields. The yields of corn and soybean from this study are presented in
Tables 17, 18, 19, 20 and 21.













Others

a. Rice yield

Puddled-flooded rice outyielded the unpuddled rice. Between the two
unpuddled rice, the yield of flooded was higher than non-flooded (Table 22).
This difference was mainly due to a greater nutrient availability of
puddled-flooded soil than unpuddled.

Among the three types of rice fields, drainage prior to harvest
showed a significant difference in yield (Table 23). The earlier the
drainage, the lower the rice yield. Late drainage (1 DBRH) resulted in an
uneven maturity of rice.

b. Weed weights and time required for handweeding

Rotovation, mulching and high crop stand significantly reduced weed
weight from no tillage plots (Tables 24 and 25). Drilling instead of broad-
casting of relay planted soybean into puddled flooded rice also significantly
reduced weeding time (Table 25).

c. Relay planting of soybean into rice.

Broadcast relay planting of soybean into non-lodged rice is a
promising method of growing soybean after rice. This method is cheap and
has a negative turnaround period. However, low crop stand is a common
problem encountered by this method. This study found that the crop stand
could be increased about 40% by increasing seeding rate from 60 to 120 kg/ha.
As mentioned earlier, seed soaking increased crop stand by 23%; drilling
soybean seeds in between rice rows increased crop stand by 15% above that
of the broadcast stand. Drilling also improved evenness of crop stand
measured by plant distribution 5.4 times over that of broadcast seeding
(Table 26).

d. Soil crusting and cracking

From visual observation, mulching and rotovation inhibited soil crust
and crack formation.


CONCLUSION


1. Soil moisture content and soil resistance of puddled-flooded rice
were higher than for unpuddled rice soil. The soil moisture content and
soil resistance of unpuddled flooded and non-flooded rice soils were similar.

2. The above differences resulted in slightly poorer crop establishment
and significantly poorer crop performance of corn grown on puddled-flooded rice
soil than the unpuddled-flooded rice soil.













3. The soil moisture content after puddled-flooded rice was significantly
affected by the time at which the field was drained prior to rice harvest.
Drainage earlier than 11 DBRH had less effect than drainage after 11 DBRH.

4. A lack or an excess of soil moisture in the 0-5 cm layer reduced
soybean stand. The maximum stands were obtained at 50-56% moisture content
at planting of no-tillage puddled-flooded rice soil.

5. A lack or an excess soil moisture in the lower layer resulted in
poor crop performance. The maximum individual soybean plant performance was
obtained at 58% soil moisture content at planting of puddled-flooded rice soil.

6. a. Bed tillage accelerated soil moisture loss, resulting in poorer
crop stand and performance than no tillage.

b. Furrow tillage provided a higher soil moisture content than no
tillage, however, the crop performance was disturbed by an imbalanced nutrient
uptake (see second paper).

c. Three rotovations greatly reduced soil moisture content in the
0-5 cm layer, resulting in 50% lower soybean stand than with no tillage.
However, the dry 0-5 cm layer acted as mulch for the lower layer, resulting in
the best individual soybean plant performance because of more moisture was
maintained in the lower zone than in no tillage plots.

d. A single rotovation gave a slightly lower crop stand but better crop
performance than no tillage. This resulted in the highest crop dry matter and
bean yield of soybean among the tillage treatments.

7. Mulching slightly increased crop stand and significantly improved
crop performance, because it reduced moisture loss and kept soil impedance low.

8. a. Relay planting of soybean into non-lodged rice fields was
promising. The poor stand of broadcast relay planted soybean could be improved
36% by increasing the seeding rate from 60 to 120 kg/ha, 23% by seed soaking
and 15% by drilling instead of broadcast seeding.

b. The drill-seeding method improved distribution of soybean stand.

9. Mulching, rotovation and high crop stand significantly reduced weed
infestation. The drill-seeding method significantly reduced hand weeding time
from the broadcast seeding method.

10. Mulching and rotovation inhibited soil crusting and cracking.





/llk
11-2-78











REFERENCES


BARKER, R.and R.W. HERDT. 1978. Rainfed lowland rice as a research
priority an economist's view. Paper prepared for the
International Rice Research Conference, April 17-21, 1978.
IRRI, Los Banos, Philippines. pp. 15.

CHANDRAPANYA, D. and G.R. BANTA. 1978. Possible cropping patterns for use
in rainfed rice areas in Asia. Paper presented at the International
Rice Research Conference, April 17-21, 1978, IRRI, Los Banos,
Philippines. pp 27.

DE DATTA, S.K., G. LEVIN and A. WILLIAMS. 1970. Water management practices
and irrigation requirement for rice. In "Rice Production Manual.'
UPCA-IRRI. pp 89-105.

DUFF, N.K. and M.N. BANDYOPADHYAY. 1966. Improving rainfed rice in India.
World Crops. 18-26.

DUDAL, R. 1968. Genesis and classification of paddy soils. In "Geography
and Classification of Soils in Asia"(Kovda, V.A. and E.V. Lobova,
eds.). Israel Program for Scientific Translation, Jerusalem.

FLORESCA, E.T. 1968. Cultural methods for soybeans grown in Maahas clay
with special reference to establishment, weed control and fertilization.
Master's Thesis. UP College of Agriculture.

FRAMJI, K.K. and I.K. MAHAJAN. 1969. Irrigation and drainage in the world.
A global review. Second edition. Vol. I. International Commission
on Irrigation and Drainage.

IRRI. 1978. Interpretive analysis of selected papers from changes in
rice farming in selected areas of Asia. Los Banos, Philippines.

KOENIGS, F.F.R. 1950. A "Sawah" profile near Bogor (Java). Center of
the General Agricultural Research Station, Bogor, Indonesia. No. 105.

MELHUISH, F M., W.A. MUIRHEAD and M.L. HIGGINS. 1976. Current views on
effects of cropping history on nutrient availability in irrigated
soils. Paper presented at Aust. Soil Sci. Soc. Conference, Wagga,
May 1976.

PALADA, M.C., R.L. TINSLEY and R.R. HARWOOD. 1976. Cropping Systems
Agronomy Program for Rainfed Lowland Rice Areas in Iloilo. IRRI
Saturday Seminar, April 24, 1976. IRRI, Los Banos, Philippines.

PATRICK, W.H. JR. and C.N. REDDY. 1977. Chemical changes in rice soils.
Paper presented at the symposium "Soils and Rice" at IRRI, Los
Banos, Philippines. Sept. 20-23, 1977.














PONNAMPERUMA, F.N. 1972. The chemistry of submerged soils. Adv. Agron.
24: 29-96.

1977. Physico-chemical properties of submerged soils
in relation to fertility. IRRI Research Paper series No. 5.

SANCHEZ, P.A. 1976. Properties and management of soil in Tropics.
Chapt. 12: Soil management in Multiple Cropping systems. John
Wiley and Sons. New York-London-Sydney-Toronto.

and R. BRADFIELD. 1970. Puddling tropical rice soils.
Effect on plant performance and nutrient uptake. International
Rice Research Conference, April 20-24, 1970. IRRI, Los Banos,
Philippines.

RITCHIE, J.T. 1972. Model for predicting evaporation from a row crop
with incomplete cover. Water Resource Research. 8:1204-1213.

ZANDSTRA, H.G. and V.R. CARANGAL. 1977. Crop intensification for the
Asian Rice Farmer. Agricultural Mechanization in Asia Summer -
21-30.

and E.C. PRICE. 1977. Research topics critical for the
intensification of rice based cropping systems. Prepared as
background paper for research programming meeting on Cropping
Systems Research at IRRI, Los Bafos. May 3, 1977.










Table 1. Monthly rainfall and pan evaporation during the uoland
crop period of the experiment and the average of previous years
at IRRI Agroclimatic Station, Los Banos, Philippines.

Characters Dec. Jan. Feb. Mar. Aor.

Rainfall (mm/mo.)
Experimental period 21.1 21.5 8.9 6.4 28.7
(0/11)/ (3/11) (4/11) (0/11) '8/11

Average (11 years) 253.6 49.4 13.6 32.8 30.1

Evaporation (mm/mo)
Experiment period 124 121 127 197 194
Average (8 years) 103 120 124 169 194

Source: Agroclimate, IRRI, Los Bahos, Philippines.
a/ x()- x = number of years that had rainfall of respective month
y below the amount during the experimental period


y = number of years used-in computing the average.

















Table 2. Soil moisture content (% ODW) from different depths at seeding and
15 DAS of relay planted soybean into puddled flooded rice. Experiment
No. 5 (Greenhouse).



Seed placement and Soil moisture content (% ODW)a/
Seed placement and
days from drainage Planting date 15 DAS
to planting date
of soybean 0-5 cm 5-15 cm 15-30 cm 0-5 cm 5-15 cm 15-30 cm


Surface laid

0 88.3a 61.3a 64.3a 48.0a 50.3a 58.3a
3 62.0 b 54.0 b 60.7 b 46.0a 49.3 b 56.7 b
6 54.0 c 53.0 b 58.7 c 42.3 b 48.0 cd 53.7 c
9 41.0 e 50.0 c 57.0 c 37.3 c 46.7 ef 52.0 c

Dibbled into 3 cm

0 85.3a 62.6a 64.3a 48.0a 50.3a 59.0a
3 66.6 b 54.3 b 60.7 b 46.7a 48.3 c 56.7 b
6 53.6 c 52.3 b 58.3 c 42.0 b 47.3 de 53.3 c
9 45.3 d 49.7 c 57.3 c 39.3 c 46.3 f 52.3 c

-/In a column, means followed by a common letter are not significantly
different at the 5% level by DMRT.












Table 3. Soil moisture content (% ODW) in the
15-30 cm depths at planting dates of
by tillage and previous rice growing
Experiment No. 1.


0-5, 5-15 and
corn, as influenced
systems.


Previous rice growing system/

Tillage Unpuddled Unpuddled Puddled
for corn non-flooded flooded flooded S1-S3b/ S2-S3
Sl S2 S3

0-5 cm
No tillage 40a 41a 45a -5** -4*
Row tillage 35 b 37 b 39 b -6** -2 ns
Complete tillage 30 c 31 c 36 c -6** -5**

5-15 cm

No tillage 49a 50a 51a -2 ns -1 ns
Row tillage 44 b 45 b 46 b -2* -1 ns
Complete tillage 41 c 42 c 43 c -2 ns -1 ns

15-30 cm

No tillage 52a 52a 56a -4* -4*
Row tillage 50ab 50ab 54ab -4* -4*
Complete tillage 48 b 49 b 53 b -5* -4*

R/In a column of a respective sampling depths, means followed
by a common letter are not significantly different at the 5% level
by DMRT.
/ significant at the 5% level by LSD.
** significant at the 1% level by LSD.
ns not significant















Table 4. Soil moisture content (% ODW) in the 0-5, 5-15 and 15-30
depths at 50 DAS of corn, as influenced by fertilizer rates,
tillage and previous rice growing systems. Experiment No. 1.


Previous rice growing systems/
Tillage and
fertilizer rates Unpuddled Unpuddled Puddled
for corn non-flooded flooded flooded S1-3h/ S2-S3b
SI S2 S3


0 5 cm

0-0-0 17.1 b 16.7 b 16.4 b 0.7 ns 0.3 ns

60-60-60 23.1a 20.9a 20.7a 2.4* 0.2 ns

5 15 cm
0-0-0
No tillage 31 c 31ab 30 c 1 ns 1 ns
Row Tillage 32 bc 31ab 33a -1 ns -2 ns
Complete tillage 34a 32a 33a 1 ns -1 ns
60-60-60
No tillage 31 c 31ab 30 c 1 ns 1 ns
Row tillage 31 c 30 b 30 c 1 ns 0
Complete tillage 33ab 32a 32ab 1 ns 0

15 30 cm
0-0-0 49.2a 49.5a 49.5a -0.2 ns 0

60-60-60 45.9 b 46.8 b 46.8 b -0.9 ns 0


a In a column of
common letter are not
/* significant
** significant
ns not signif


respective sampling depths, means followed by a
significantly different at the 5% level by DMRT.
it at the 5% level by LSD.-
it at the 1% level by LSD.
icant









Table 5. Turnaround period (days) between harvesting of rice
and planting of corn as influenced by tillage and previous rice
growing systems. Experiment No. 1.

Previous rice growing condition-
Unpuddled Unpuddled Puddled
Tillage non flooded flooded flooded b/ b/
for corn S1 S2 S3 S1-S3- S2-S3-


No tillage 2a 1 c 2 c 1ns 1ns
Row tillage 2a 4 b 6 b 4** -2*
Complete tillage 2a 6a 9a 7** -3*



a/ In a column means followed by a common letter are not signi-
ficantly different at the 5% level.


b/ = significant
** = significant.
ns = not significant


at the 5% level.
at the 1% level.


Table 6. Turnaround period (days) between harvesting of rice
and planting of soybean as influenced by tillage and drainage
prior to harvest of previous rice. Experiment No. 3.

a!
Tillage for No.of days from drainage to rice harvest-/
soybean 21 11(control) 1


No tillage (control) la la 2a
Furrow tillage 3 b 3 b 4 b
Bed tillage 3 b 3 b 4-b
One rotovation 4 c 4 c 9 c
Three rotovations 4 c 4 c 11 d



a/ In a column, means followed by a common letter are not
significantly different at the 5% level.













Table 7. Soil moisture contents (% ODW) in different depths at 10 and 55 DAS of
corn grown after puddled-flooded rice, as influenced by fertilizer
rates, mulching and depths of fertilizer placements. Experiment No. 2.


Fertilizer rates, 10 -AS 55 DAS
mulching and within depths (cm)a7 within depths (cm)81
fertilizer 0-5 5-15 15-30 0-5 5-15 15-30
placements


0-60-60, No mulch
5 cm
20 cm
Mulch
5 cm
20 cm
60-60-60,No mulch
5 cm
20 cm
Milch
5 cm
20 cm
120-0-60,No mulch
5 cm
20 cm
Mulch
5 cm
20 cm
120-60-60 No Mulch
5 cm
20 cm
Mulch
5 cm
20 cm


28.0 b 41.0 cd
28.3 b 41.3 bcd

33.3a 42.7abc
33.7a 42.3abc

27.3 b 41.0 cd
27.7 b 42.0abc

33.3a 43.0abc
34.0a 43.0abc

27.0 b 40.0 d
27.0 b 41.7abcd

33.0a 43.7a
33.3a 43.7a

27.3 b 41.0 cd
27.0 b 41.7abcd

33.0a 41.7abcd
33.3a 43.3ab


51.7a 17.7
51.3a 21.0

52.3a 26.0 cd
52.3a 26.3 bc


50.3a 20.0
51.3a 21.0


51.7a 25.3 cd
52.7a 26.3 bc


50.7a 21.7
50.3a 21.0

51.7a 26.0
51.3a 27.7al

51.Oa 25.0
52.0a 24.7

51.Oa 28.7a
51.3a 28.7a


g 24.3
ef 25.3


34.0a
33.7a

27.0
27.3


33.3a
33.0ab

29.3 d
28.7 d


cd 31.7 c
31.7 c

cd 29.3 d
d 29.3 d

31.3 c
32.0 bc


43.3 bc
32.7 cde


45.0a
43.3 bc


42.0 def
41.7 efg

44.3ab
42.7 cde


41.0
41.0


43.3 bc
40.7


41.3
39.7

43.0
41.0


a/In a column, means followed
different at the 5% level by DMRT.


by a common letter are not significantly







Table 8. Resistance to cone penetrometer (kg/sq cm) at different
depths and planting times of no tillage soybean grown after puddled
flooded rice as influenced by rice straw cutting. Experiment No. 7.


Planting .times
(days) after har- 0 cm 10 cm 20 cm
vesting of rice C1 C2 C1 C2 C1 C2


0 <0.8 <0.8 <0.8 <0.8 1.1 1.2
2 <0.8 <0.8 <0.8 <0.8 1.3 1.4
4 0.8 <0.8 .1.0 1.0 1.4 1.5
6 <0.8 <0.8 1.2 1.2 1.6 1.8
8 40.8 <0.8 1.4 1.3 1.9 2.0
10 1.5 <0.8 1.6 1.5 2.5 2.6
12 2.4 1.3 1.9 1.8 3.5 3.0
14 3.5 1.9 2.7 2.4 4.2 3.6
16 4.9 2.6 3.5 3.3 5.5 4.4
18 5.3 3.4 4.7 4.2 6.4 5.3


= straw
= straw


was cut
was cut


to the
to the


base at
base at


harvesting of rice.
respective planting times .


Table 9. Depth (cm) to obtain the resistance to cone penetrometer
of 2 kg/sq cm at 5 DAS of corn as influenced by tillage and pre-
vious rice growing systems. Experiment No. 1.


Previous rice growing system-a/
Unpuddled Unpuddled Puddled
non-flooded flooded flooded
Sl S2 S3


Sl-S3b S2-S31


No tillage 22.2a 21.8a 20.Oa 2.2* 1.8ns
Row tillage 20.9a 17.7 b 17.5 b 3.4** 0.2ns
Complete tillage 20.6a 14.0 c 13.7 c 6.9** 0.3ns


a/ In a column, means followed by a common letter
ficantly different at the 5% level by DMRT.


/ns not significant
significant
** significant


are not signi-


at the 5% level by LSD.
at the 1% level by LSD.


Tillage!
for corn











Table 10. Percent of established plant at 5, 9, and 15 DAS
of relay planted soybeans into puddled-flooded rice, as in-
fluenced by seed placements and drainage prior to soybean
planting. Experiment No. 5.
a/
Seed placements and days Percent of established plant
from drainage rice pot 5 9 15
to planting of soybean DAS DAS DAS

1. Surface 0 day 56a 62ab 62a
2. Surface 3 days 34ab 41 c 42 b
3. Surface 6 days 22 b 26 d 26 c
4. Surface 9 days 3 d 8 e 8 d

5. 3 cm 0 day 40a 54 bc 55ab
6. 3 cm 3 days 37a 74a 81a
7. 3 cm 6 days 24 b 61ab 61a
8. 3 cm 9 days 12 c 58 b 58a



aIn a column, means followed by a common letter are not
significantly different at the 5% level by DMRT.







Table 11. The average number of plants per sq m at 10
DAS and 2 DBh of relay planted soybean into puddled
flooded rice as influenced by seeding methods, seed
soaking and seeding rates. Experiment No. 4.


Seeding methods, a/ a/
seed soaking and 10 2
seeding rates DAS DBH


Broadcast, unsoaked

60 kg/ha 43 g 42 g
120 kg/ha 61 cd 61 cd

Broadcast, soaked
60 kg/ha 48 f 47 f
120 kg/ha 65 bc 64 bc
Drill, unsoaked
60 kg/ha 53 e 53 e
120 kg/ha 68 b 67 b
Drill, soaked
60 kg/ha 58 d 58 d
120 kg/ha 88a 88a


a/ In a column, means followed by a common
not significantly different at the 5% level


letter are
by DMRT.


Table 12. Number of soybean plants per square meter at
10 DAS as influenced by tillage and drainage prior to
harvest of previous rice. Experiment No. 3.


No. of days from drainage
Tillage for to harvesting of rice,/
soybeans 21 11(control) 1


No tillage (control) 53 b 60a 60a
Furrow tillage 49 c 48 d 48 c
Bed tillage 53 b 52 c 51 bc
One rotovation 58a 56 b 52 b
Three rotovations 32 d 33 e 33 d


SIn a column of respective observation dates, means
followed by a common letter are not significantly diffe-
rent at the 5% level by DMRT.






Table 13. Number of soybean plants per sq m at 10 DAS and at
harvesting, as influenced by planting methods and mulching.
Experiment No. 5.


Planting methods At
and mulchings 10 DAS-/ harvest/-


Drill-relay planting
No mulch 28.4 c 28.0 c
Mulch 30.6 c 30.4 c
No tillage-sequential planting
No mulch 55.3a 55.0a
Mulch 55.9a 55.8a
Furrow-tillage-sequential planting
No mulch 45.6 b 45.6 b
Mulch 42.6 b 42.3 b
One rotovation-sequential planting
No mulch 49.1 b 48.4 b
Mulch 55.0a 54.6a


a/ In a column, means followed by a common letter are not
significantly different at the 5% level by DMRT.


Table 14. Dry weight of above ground part at 20 DAS
relay planted soybeans into puddled flooded rice, as
influenced by seed placements and drainage prior to
soybean planting. Experiment No. 5.


Seed placements and days
to drain rice pot before
planting of soybeans


Dry matter
weight a/
(g/plant)


1. Surface 0 day
2. Surface 3 days
3. Surface 6 days
4. Surface 9 days


5. 3 cm


- 0 day


6. 3 cm 3 days


7. 3 cm
8. 3 cm


- 6 days
- 9 days


a/ In a column means followed by a common
letter are not significantly different at the
5% level by DMRT.


1.72ab
1.60ab
1.06 bc
0.31 d

1.70ab
2.14a
1.23 b
0.62 e



















Table 15. Dry matter weight of soybean(g/sq m) at 63 DAS, as
influenced by tillage and drainage prior to harvest


of previous rice.


Experiment No. 3.


No. of days from drainage to
Tillage for harvest of ricea
Tillage for
soybean 21 11 1 11-21b 1-11b
(control)


No tillage
(control) 123.3 b 152.0a 177.9 b 28.7** 25.9**

Furrow tillage 62.9 d 78.6 b 94.4 d 15.7** 15.8**

Bed tillage 69.3 c 82.5 b 104.4 c 13.2** 21.9**

One rotovation 133.2a 154.0a 183.5a 20.8** 29.5**

Three
rotovations 129.6a 151.9a 172.8 b 22.3** 20.9**



Means 103.7 123.8 146.6


aln a column, means followed by a common letter are not
significantly different at the 5% level by DMRT.


b significant
** significant
ns not significant


at the 5% level by LSD.
at the 1% level by LSD.
















Table 16. Dry matter weight of soybean plants
(g/sq m) at 63 DAS, as influenced by planting
methods and mulching. Experiment No. 6.


Planting methods
and mulchings


Drill-relay planting
No mulch
Mulch
No tillage-sequential planting
No mulch
Mulch


Furrow-tillage-sequential planting
No mulch
Mulch
One rotovation-sequential planting


No mulch
Mulch


Total a/


71.9
136.7


165.5
235.8a


56.3
54.7


208.9 b
242.0a


a/ Means followed by a common letter are not
significantly different at the 5% level by DMRT.














Table 17.


Grain yield (kg/ha) of corn as influenced by fertilizer
rates, tillage and previous rice growing systems.
Experiment No. 1.


Previous rice growing systems
Fertilizer rate Unpuddled Unpuddled Puddled -S b S2-S3b
and Tillage for non-flooded flooded flooded
corn S a S2a S3a
S1 S2


0-0-0

No tillage 316 d 338 c 276 b 40 ns 62 ns
Row tillage 288 d 339 c 313 b 25 ns 26 ns
Complete tillage 345 d 398 c 254 b 91 ns 144 ns

60-60-60

No tillage 1726 b 2438a 1516a 210* 922**
Row tillage 1301 c 2032 b 1587a -786** 445**
Complete tillage 2175a 2516a 1698a 477** 818**



aIn a column, means followed by a common letterare not significantly
different at the 5% level by DMRT.


bns not significant
significant
** significant


at the 5% level by LSD.
at the 1% level by LSD.









Table 18. Grain yielda/of corn (kg/ha) grown after puddled
flooded rice, as influenced by fertilizer rates, mulchings


and fertilizer placements.


Experiment No. 2.


Fertilizer No mulch Mulched
rate 5 cm 20 cm 5 cm 20 cm


0-60-60 381 f 628 f 553 f 1015 e
60-60-60 1141 e 2048 e 1838 cd 2819 b
120-0-60 1033 e 1994 cd 2001 cd 2067 c
120-60-60 1738d 2850b 2639b 3150a


a/ Means followed by a common letter
different at the 5% level by DMRT.


Table 19.


are not significantly


Grain yield (kg/ha) of soybeans as influenced by
tillage and drainage prior to harvest of previous
rice. Experiment No. 3.


Number if days from drainage
Tillage for to harvest of rice a
Meana
soybean
21 11 1
(control)


No tillage
(control) 1004ab 1157a 1247 b 1136 b

Furrow tillage 463 c 470 c 559 d 497 e

Bed tillage 530 c 613 c 634 d 593 d

One rotovation 1099a 1199a 1396a 1231a

Three rotovation 903 b 886 b 1076 c 955 c

Means 800ns 865 982*

aln a column, means followed by a common letter are not
significantly different at the 5% level by DMRT.


b significant
ns not significant


at the 5% level by LSD.







Table 20. Grain yield of soybean as influenced by
planting methods and mulching. Experiment No. 6.


Planting methods
and mulchings


Drill-relay planting
No mulch
Mulch
No tillage-sequential planting
No mulch
Mulch
Furrow tillage-sequential planting
No mulch
Mulch
One rotovation-sequential planting
No mulch
Mulch


Grain yield-!
(kg/ha)


520 d
1088 c


1374 b
1895a


377
271


1637ab
1968a


a/ Means followed by a common letter are not signi-
ficantly different at the 5% level by DMRT.


Table 21. Grain yield of soybean relay planted into
puddled-flooded rice, as influenced by different
seeding methods, seed soaking and seeding rates.
Experiment No. 4.


Seeding methods, seed soak-
ings, and seeding rates


Broadcast, unsoaked
60 kg/ha
120 kg/ha
Broadcast, soaked
60 kg/ha
120 kg/ha
Drill, unsoaked
60 kg/ha
120 kg/ha
Drill, soaked
60 kg/ha
120 kg/ha


Grain yield-/
(t/ha)


1.31
2.12 bc


1.55
2.22 b


1.77
2.24 b


2.02
2.61a


a/ Means followed by a common letter are not signi-
ficantly different at the 5% level by DMRT.











Table 22. Grain yield of rice as influenced by rice
growing systems. Experiment No. 1.


Rice growing Grain yield/
systems (t/ha)


Unpuddled non flooded 4.57 b

Unpuddled flooded 4.62 b

Puddled flooded 5.81a



a/Means followed by a common letter are not signifi-
cantly different at the 5% level by DMRT.


Table 23.
different
harvest.


Grain yield of rice as influenced by
time to drain rice field prior to its
Experiment No. 3.


Days from drainage Grain yield-
to rice harvest (t/ha)


21 3.51 c

11 4.08 b

1 4.41a



a/Means followed by a common letter are not sig-
nificantly different at the 5% level by DMRT.


















Table 24. Dry weight of weeds at 29 DAS of soybean as
influenced by planting methods and mulching. Experi-
ment No. 6.


Planting methods Dry weight of weedsa/
and mulching (g/sq m)


Drill-relay planting
No mulch 120a
Mulch 53 b

No tillage-sequential planting
No mulch 115a
Mulch 52 b
Furrow tillage-sequential planting
No mulch 35 b
Mulch 6 c
One rotovation-sequential planting
No mulch 3 d
Mulch 2 e


not signifi-


/Means followed by a common letter are
cantly, different at the 5% level by DMRT.







Table 25. Dry weight of
handweeding at 29 DAS of
puddled flooded rice, as
seed soaking and seeding


weeds and time required for
soybean relay planted into
influenced by seeding methods,
rates. Experiment No. 4.


Seeding methods, Dry weed Time to
seed soaking, & weight/ weeding/
seeding rates (g/sq m) (hr/ha)-


Broadcast, unsoaked
60 kg/ha 156a 327a
120 kg/ha 89 bcd 233 cd

Broadcast, soaked
60 kg/ha 123ab 300ab
120 kg/ha 49 de 187 e

Drill, unsoaked
60 kg/ha 156a 313ab
120 kg/ha 71 cde 200 de

Drill, soaked
60 kg/ha lOlabc 273 bc
120 kg/ha 52 e 167 e


a/ In a column, means followed by a common letter are
not significantly different at the 5% level by DMRT.
b/ Observation was done in minutes/25 sq m.



Table 26. Comparison of sampling variance between broadcast
and drilling planting methods of soybean relay planted into
paddy rice. Experiment No. 4.

Sampling variance F. test for
(48 df) homogeneity of
Characters Broadcast Drilling variance


No. of soybean plants
per sq m at 10 DAS 387.8438 71.5990 5.42**

No. of soybean plants
per sq m at 2 days
before harvest 384.3750 71.1146 5.41**


** Significantly different at 1% level.








Exp. No.


SI
2
3

4

5
6

7
Pan evaporation (mm)


I-
L.
r"
L_


-L--


Rice-direct seeded

Rice -transplant
Rice transplant

Rice-transplant
Rice -transplant

Rice-transplant

| Rice-transplant


I/


T


,- Soybean

Soybean
Soybea ann

S-SoybE


Con


n


liz


Temperature (oC)


1ISoybean


8 Maximum temp.
Minimum temp.



4-


2-

0 -

Solar radiation (g cal/sqcm/day xlOOO)
51


O0
22


Rainfall (mm)


27 32 37 42 47 52 5 10 15
JUNE-- JULY-4- AUG--- SEPT-+- OCT---- NOV--- DEC-4- JAN---- FEB--- MAR--- APR-4

1977 1978

Fiqure 1. The cropping pattern and the climatic conditions during the course of the
experiments.


n


a-- --. ..


,____.
,----
L--,--
r---


!an ~7


W-


---


i J















S= seed


Depth (cm)
O0
10

20-
30


Furrow tillage


Bed tillage


One rotovation


Three rotovations


Fig. 2. Schematic of tillage treatments and the location of soybean seed. Experiment No. 3.


No tillage


WWCP0,


%*#W1


' .
';
~:~


V














Soil moisture content (% ODW)
70 I


p.-...---


60 -


50--


40 --


OW- -
C4
-. P -~


no tilage
-.-- furrow tillage
--- bed tillage
I-- Ixrotovation
-....... 3xrotovations


0 0-5cm
0 5-15cm
V 15-30cm


Drainage: days prior to rice harvest


Soil moisture content at soybean
influenced by tillage treatments
drainage prior to rice harvest.


planting, as
and times of
Experiment No.3.


20 H-


Figure 3.















Soil moisture content (% ODW)


no tili


age
;lI


UIoIw II U e
bed tillage
I x rotovation
3x rotovations


0-5cm
0 5-15cm
V 15-30cm


-


rS.
-- )ci --


- PWP


-" S."


- .- -~sn..i~~ 4U-- ---'.


10o-


21 11 I
Drainage: days prior to rice harvest

Figure 4. Soil moisture content at 40 DAS of soybean, as
influenced by tillage treatments and times of
drainage prior to rice harvest. Experiment No. 3.


,-FC.


30 -


20 -














Soil moisture content (% ODW)
50
5 -'---------------------


40 H-


-PWP


----..------- .----. ..


-- no tillage
furrow tillage
----- bed tillage
----- Ix rotovation
........ 3x rotovotions


0-5cm
0 5-15cm
V 15- 30cm


Drainage: days prior to rice harvest


Soil moisture content at 60 DAS of soybean as
influenced by tillage treatments and times of
drainage prior to rice harvest. Experiment No. 3.


10 F-


Figure 5.










Soil moisture content ( % ODW)
601


1EUUCmms .a.uu.

4`


no tillage relay
no tillage sequential
--- furrow tillage
--- I x rotovation


* no mulch
0 mulched


) 10 40 60
Time ( DAS) of soybean


Soil moisture content in the 0-5 cm layer at
soybean planting as influenced by tillage and
mulch treatments. Experiment No. 6.


E C.













- PWP


20 1-


10 h-


Figure 6.












Soil moisture content (% ODW )
601


--FC.


40 -


30 F-


- PWP


no tillage relay
no tillage sequential
furrow tillage
Ix rotovation


* no mulch
O mulched


10 40 50
Time ( DAS) of soybean
Figure 7. Soil moisture content in the 5-15 cm layer at
planting as influenced by tillage and mulch
treatments. Experiment No. 6.


20 1-


10 --


l~l)e
1111~~













0 ,* 0


10 0 so 1

AID A 20 \ \






50 S 30




0 50 I--- ---
I 2 3 4 5 6 7 78 2 3 4 5 6 7 7.8
S1 Resistance (kg/sq cm) S2

Figure 8. penetrowneter resistance at different times after rice harvest. S = straw was removed at
rice harvest; S2 = straw was removed at soybean planting. Experiment No. 7.


Depth (cm)


Depth (cm)














Depth (cm)
O .., SM-r .._.. MI
0
--- S = No tillage-relay-drill
S2M2 2 S= No tillage-dibbled segnential

10 Sl' S3 = Furrow tillage dibbled- egnentiol
**, S4 = IX rotovating-dibbled-segnential
-' MI = no mulch
20 M2= mulch


25 I I I I
S 2 3 4 5 6 7 78
0

S4MI
Figure 9. Penetrometer resistance as influenced
***. by tillage and mulch treatments at
10 ----""" -"-"-., S 40 DAS of soybean after puddled
---.... flooded rice. Experiment No. 4.



20 4M...................
20

25 I I I I I I I
I 2 3 4 5 6 7 7.8
Resistance Kg/sqm









Depth (cm)
O nK


V t's S3T3 .
2 0 -b-m




II I l III, IL
S3T2 SIT3 ^

30 S3T1 1 S-


I 2 3 4 5 6 7 78
0
Resistance Kg/sqcm

S2 = after unpuddled- flooded rice -- TI = no tillage
10 -- T2 = row tillage

o ---. T3= complete tillage

20 ***Figure 10. Penetrometer resistance as in-
a r*,**S2T3 fluenced by rice growing systems and til-
I~, ''"-'.'m... ** lage treatments at 5 DAS of corn. Experi-
22OT n'o"w"" ""* ment No. 1.
30 t


I 2 3 4 5 6 7 78


Resistance Kg/sqcm

















Resistance to cone penetrometer (kg/sq cm)


AFTER PUDDLED
FLOODED RICE


AFTER UNPUDDLED NON-
FLOODED RICE
--. no tillage -- no tillage .^
*-.* 2 x rotovationsJ m '--2 x rotovationsl


5[-


I I .I I


I I I


Soil moisture content (% ODW )


Figure 11.


Relationship between soil moisture content and penetrometer resistance as
influenced by rice growing systems, tillage treatment depths. Experiment
No. 1.


7 -

6 -


32-


m -'- m


**,% 1 4 % %


32
2-












Established plants (%)
100
FC = field capacity
PWP = permanent wilting point

80-


6
60
O


Y = 10.728 + 1.594 X
R2= 0.92**
Rxy= 0.96 '


A
Y = 163.015-1.326X
R2= 0.96*
Rxy = 0.98**


PWP
I


Soil moisture content within 0-15 cm layer at planting (ODW)


Figure 12.


Relationship between soil moisture content and soybean establish-
ment under no tillage after flooded rice. Experiment No. 7.











Established plant (%)
1001


After puddled flooded
A
Y= 5.87 + 1.91X
R2= Q77**
Rxy= 0.88


90-
After unpuddled non flooded
Y = 38.98 +141 X
R2 = 0.72 **
Rxy = 0.85" y


-L_- After unpuddled flooded

0 Y= 29.51 + 1.58X
R2= 0.89**
Rxy= 0.94*


70Q1 I I
20 30 40 50 (


Soil moisture content at planting 0-5 cm (%ODW)


Figure 13. Relationship between soil moisture and corn establish-
ment as influenced by rice growing systems. Experi-
ment No. 1.


80 -


0 )













Total dry matter wt (g/plant)
5f


41-


3 -


A 2
Y -15.557 + 0.698 X -0.06 X

R2= 0.97 **


30 40 50 60

Soil moisture content within 5-15 cm at planting (% ODW)

Figure 14. Relationship between dry matter per plant and soil moisture
content. Experiment No. 7.















Total dr
260



220



180



140-



100



60-
30


y matter (g/sqm)


Figure 15.


40 50 60 70 80 90 10
Soil moisture content within 5-15cm at planting (% ODW)

Relationship between total dry matter per square meter and
soil moisture content. Experiment No. 7.



















Dry matter (g/plant)
61


5H


3H


2 -


Figure 16.


Drainage date prior to rice harvest (days)

Dry matter per plant of soybean as in-
fluenced by drainage and tillage treat-
ment. Experiment No. 3.


I~e.


Bed tillage



Furrow tillage













2


l = unpuddled non flooded NT = no tillage
RT= row tillage
ii = unDuddled flooded CT = complete tillage


25 -g / m ::
Hil 0-0-0
+ + 600 II = puddled flooded +=60-60-60

jNT CT


i CT RT

400 iiii
15 NT i i
+ RT
iiii I +
300



200 | I 2
ii=i iiiii





5M
11 iii
-iii 11:|::
I ii 2100 -



i _ii_ 1ii




a 100 seed weight b. Total dry matter weight

Figue 17. Seed weight and total dry matter per sq m of corn as influenced by rice growing
systems, tillage, and fertilizer treatments. Experiment No. 1.


g/100seeds




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