• TABLE OF CONTENTS
HIDE
 Historic note
 Main














Group Title: Agronomy research report - University of Florida Institute of Food and Agricultural Sciences ; AY-92-01
Title: The effects of two cropping systems on nematodes and crop nutrition of soybean
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00056102/00001
 Material Information
Title: The effects of two cropping systems on nematodes and crop nutrition of soybean
Series Title: Agronomy research report
Physical Description: 25 leaves : ; 28 cm.
Language: English
Creator: Gallaher, Raymond N
Terry, E. R
McSorley, R ( Robert )
University of Florida -- Agronomy Dept
Publisher: Department of Agronomy, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1992?]
 Subjects
Subject: Cropping systems -- Florida   ( lcsh )
Soybean -- Diseases and pests -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (leaves 13-14).
Statement of Responsibility: R.N. Gallaher, E.R. Terry, Jr., and R. McSorley.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00056102
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 62628082

Table of Contents
    Historic note
        Unnumbered ( 1 )
    Main
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






AG-

Agronomy Research Report AY-92-01

The Effects of Two Cropping Systems on Nema odeJTt Skr* -~ PIiti
of Soybean ---_--- .

R.N. Gallaher, E.R. Terry, Jr., and R. McSorley Professor of
Agronomy, Graduate Assistant in Horticulture and Professor of
Nematology, Inst. Food & Agr. Sci., Univ. of Florida,
Gainesville, FL 32611.

ABSTRACT

The dynamics of cropping system effects on nematode numbers
and subsequent changes in mineral nutrient concentration and
content within different portions of plants is not well documented.
The objectives of this study were to determine (i) crop nutrition-
nematode relationships of soybean (Glycine max [L.] Merr.) in two
cropping system histories and (ii) determine the uptake and content
of plant nutrients in a cover crop of soybean and the potential
fertility value of the soybean as a green manure for a succeeding
summer corn (Zea mays L.) crop. In the first system a spring
soybean planting was made into an area that had been in a 3 year
rye (Secale cereale L.) corn double cropping system. In the
second system a spring soybean planting was made into an area that
had been planted for 4 years in a winter intercrop of wheat
(Triticum aestivum L.) and crimson clover (Trifolium incarnatum L.)
with 3 years of soybean or grain sorghum (Sorghum bicolor FL.1
Moench) as summer crops and the fourth year summer crop of corn or
grain sorghum. The second system was further divided by (i) plots
displaying visual symptoms of nematode infection designated (+) and
(ii) plots with a healthy visual appearance designated (-).
Soybeans following rye, crimson clover (+), and crimson clover (-)
had high, intermediate and low mean numbers of root-knot nematodes
(Meloidogyne incognita [Kofoil and White] Chitwood) with values of
842, 432 and 81.5 per 100 ml soil aliquot, respectively. Whole
plant dry matter yields were 343, 806 and 1422 g m-2 for (+), (-),
and rye, respectively. Leaf N and leaf and pod K were
significantly reduced with each increase in number of nematodes.
Leaf N values were 40.71, 35.48 and 29.10 g kg.,, leaf K values were
16.40, 8.55 and 5.97 g kg'' and pod K values were 19.23, 14.50 and
9.20 g kg'1 for rye, (-) and (+), respectively. Increasing
concentration of leaf Ca and Mg occurred with increasing numbers of
nematodes. Values for leaf Ca and Mg were 11.55, 14.15, 16.48 and
3.52, 5.12, 6.13 g kg'', for rye, (-), and (+), respectively.
Content of minerals was highest in the soybeans following rye. The
leaf and stem portions had the greatest content of nutrients.
Content in leaf and stem N, P, Ca, Zn and leaf portions of K and Mg
were significantly lowered with increases in nematode numbers.
Effects of nematodes became more apparent with age and content
significantly decreased with increasing numbers of nematodes in the
nutrients N, P and K. Soybean grown after rye had the highest
gains in content over time. Total whole plant contributions of
soybean following rye at 104 days after planting for N, P, and K
were 338.3, 46.5 and 208.3 kg ha'1, respectively. Contribution of









N, assuming 65% recovery for the succeeding corn crop, would be 220
kg ha'.

INTRODUCTION

I Nematodes and Mineral Nutrition

Plant parasitic nematodes are recognized for their damage to
numerous plant species. They attack the roots of their host plants
and cause disruptions and changes in plant tissues and interfere
with physiological processes. Attempts made to restore yields of
infected wheat (Triticum aestivium L.) by the addition of
fertilizer were not successful (Doyle et al. 1987). Similarly in
beans (Phaseolus vulgaris L.) a 4X rate of potassium Nitrate was
required for infected plants to yield similar to "normal" plants.
One notable effect of nematodes are the nutritional alterations in
the host plant. Change in nutrient concentrations is one of the
first effects of nematodes on the host (Melakeberhan et al. 1987).
For normal processes and growth to occur the proper levels of
mineral nutrients must be taken up by plants. Many abnormal
functions and symptoms are related to nutritional disfunction. The
distribution of mineral nutrients in nematode infested plants is
affected by host plant, nematode species, and the mineral nutrition
of the host (Melakeberhan et al. 1987; Viglierchio, 1987)

The infestation of rice (Oryza sativa L.) with Heterodera
oryzicola L. and Meloidoqyne graminicola L. resulted in reductions
of concentrations in N, P, and Fe in roots and shoots of the
infected plants (Rao et al. 1988). Meloidoqyne spp. specifically
led to concentration reductions in K, Mn, and Mg in shoots while
increasing the same in the roots. The cyst nematode (Heterodera
spp.) infected plants displayed increased Ca in the shoots and
roots. Both nematode species resulted in leaf chlorosis due to
decreased N and P uptake (Rao et al. 1988). In potato (Solarum
tuberosum L.) concentration of N, P and K decreased while Ca
concentration increased subsequent to inoculation with Globodera
pallida L. (Been and Schomaker, 1986). Another study of potatoes
with nematodes demonstrated decreased tuber production and
decreased P, K and Mg uptake while Ca uptake was increased (Fatemy
and Evans,1986).

Melakeberhan et.al. (1985, 1987, 1988) have done several
studies of nutrient concentration and content as affected by the
rootknot nematode, Meloidoqyne incognita, in the common bean.
Depending on the type of experiment, analysis used and portion of
the plant, these studies had variable results. Nitrogen
concentration in the whole plant and roots, and root Cu and Zn
decreased with nematode infection. Shoot Ca, Cu, and Fe increased
with the increasing nematode numbers while K, Mn, and Zn and all
elements in the roots decreased (Melakeberhan 1985). In a second
study using nondestructive assays shoot K and Fe concentration
decreased with additional levels of nematodes while the opposite








effect occurred in the roots. Calcium levels were lowered in the
shoots for like reasons. Manganese, Cu and Fe showed variable
trends. Using nondestructive assay higher levels of nematodes were
expressed by decreased concentrations of K, Zn and Mn as well as
increased Ca (Melakeberhan et al. 1987).

Overall elemental content of nematode infected plants
generally decreases with the increasing levels of nematode
infection, which is due mainly to decreased dry matter production
(Melakeberhan et al. 1985; Melakeberhan et al. 1987). Up to 50 %
decreases in leaf and stem dry weight and the number of seed pods
has been observed in the common bean infected with root-knot
nematodes (Melakeberhan et al. 1988).

Root-knot nematodes (Meloidoqyne spp.) are a serious pest in
soybean (Glycine max L. Merr.) It has recently been observed that
soybeans following a winter cover crop of crimson clover (Trifolium
incarnatum L.,) had substantial populations of Meloidogyne
incognita. The soybeans were severely damaged by the parasites
which resulted in decreased dry matter and decline in health of the
plants. These problems were not apparent in soybean following a
winter cover crop of rye (Secale cereale L.) (McSorley and
Gallaher, 1991). These observations reinforce the need for studies
on the nutritional effects of nematode on soybean as determined by
previous cover crop.

II Soybean as a Green Manure

Legumes are often used in crop rotations for residual N
effects and are incorporated as green manures. Increases in non -
legume grain yields by previous growth of legume crops are well
documented (Badaruddin and Meyer, 1989). In one situation forage
legumes were cut for hay and the crowns and roots were incorporated
as green manure. Nitrogen content of the crowns and roots ranged
from 63 to 86 kg/ha for sweet clover (Melilotis officinalis L.) and
likewise 33 to 78 kg/ha in red clover (Trifolium pratense L.)
(Badarrudin and Meyer 1989). Under a wheat summer mungbean
(Vicia radiata L. Wilcezk) -rice system with no supplemental N,
when the mung straw was removed rice yields were 3.2 t/ha. If the
mung straw was incorporated as a green manure, rice yields were 6.5
t/ha (Kulkarni and Pandey, 1988).

According to Bouldin (1988) green manure is primarily used as
a valuable source of N to succeeding crops. Once a legume is
incorporated into the soil under hot, humid conditions
decomposition is rapid and N becomes available in seven to 10 days
(Pandey and Pendleton, 1986) A second virtue of green manure is
the residual N effects (Bouldin, 1988). Some of the organic matter
decomposes more slowly and subsequently accumulates in the soil,
becoming a residual source of N. Estimates are that after 10 years
of incorporating green manure at 100 kg/ha, an equivalent of 10
kg/ha of residual N in addition to the 65 kg/ha from the previous








application would be available as mineral N (Bouldin 1988).

In many cropping systems green manure is suitable for partial
replacement of inorganic fertilizer sources (Pandey and Pendleton
1986) High rice yields have been maintained while 25 to 50 % of N
came from green manure of mungbean, cowpea (Vigna unguiculata [L.
Walp.) and blackgram (Viana mungo L.) (Kulkarni and Pandey, 1988).
Experiments using alfalfa (Medicaqo sativa L.) and red clover as
green manure resulted in corn (Zea mays L.) yield equivalent to
those using 90 125 kg/ha of fertilizer N (Bruulsema and Christie,
1987).

Soybean has been evaluated as a green manure under several
different cropping situations. Soybean in an intercrop with corn
was turned under adjacent to rows of corn; consequently the corn
yields increased 600 kg/ha over the control. The soybean
contribution was equivalent to 28 kg/ha of N fertilizer (Pandey and
Pendleton, 1986). Soybean has potential as a green manure for
tropical and warm temperate climates proceeding high nutrient
requirement crops such as corn. Another grain legume, cowpea, has
been evaluated for nutritional value for a subsequent rice crop.
Nutrient uptake of rice under a rice rice cowpea system was
71.1, 15.3 and 73.2 kg/ha of N, P, and K, respectively. A rice -
rice rice system resulted in uptake of 69.5, 14.9, and 72.9
kg/ha, respectively (Kulkarni and Pandey, 1988). Soybean should
perform similarly.

The objectives of this investigation were; 1) to determine the
crop nutrition nematode relationships for soybean in two cropping
system histories and 2) determine the uptake and content of plant
nutrients in a cover crop of soybean and the potential fertility
value of the soybean as a green manure for a succeeding summer corn
crop.

MATERIALS AND METHODS

Two soybean experiments on the Agronomy Farm near Gainesville,
Fl. were studied. Crops were grown on an area dominated by
Grossarenic and Arenic Paleudults (Soil Survey Staff, 1984). Four
replications of each study were sampled for plant and soil nutrient
relationships and nematodes.

Cropping System One

The first cropping system was on an area that had been in a
rye- corn double cropping system for the past 3 years. In 1990
soybean was substituted for corn in a rye soybean double cropping
system. The cover crop of 'Wrens Abruzzi' rye was mowed at full
bloom and a blend of 15 20 soybean varieties (Hiebsch, 1990) was
planted into the mulch with a "Tye" no-tillage drill an 2 April
1990. Soybean were planted at 135 kg ha'1 in 25 cm wide rows to
serve as a cover crop for a summer tropical corn breeding nursery.








Labeled rates of paraquat (Gramoxone) (paraquat dichloride (1,1'-
dimethyl-4-4'-bipyrdinumdichloride), metolachlor (Dual) (2-chloro-
N-(2-ethyl-6-methyl-phenyl)-N-(2-methoxy-l-methylethyl)acetamide,
and metribuzin (Lexone) (4-amino-6(1,1-dimethylethyl)-3-
(methylthio)-l,2,4-triazin-5(4H)-one) with a non ionic surfactant
were sprayed preemergence to control weeds. One application of
acephate (Orthene) (O,S-dimethyl acetyl phosphoramidothioate) was
used when the beans were in the R1 stage to control grasshoppers,
Schistocerca americana Drury (Borror and White, 1970).

On 24 June, four samples of soybean at the R1 stage (Fehr and
Caviness, 1977) were taken at random from 1-m2 areas. Samples from
this first date were used to obtain whole plant dry matter yields
and nutrient concentration of whole soybean plants at 72 days after
planting (DAP). Whole plants were hand pulled to include extracted
roots. Samples were dipped in water to remove soil contaminants
and dried at 70 C in a forced air oven until dry. Plants were
weighed for dry matter yield, chopped in a hammer mill, subsampled
and ground in a Wiley mill to pass a 2mm stainless steel screen. A
subsample was stored in sterile air tight bags for subsequent N and
mineral analysis. Samples were again taken from 1 m areas at
random from four locations at the R4 stage of growth prior to
converting the soybean crop to green manure on 15 July. These
samples were used in the determination of concentration of
nutrients in plant parts at 104 DAP. Samples were prepared
similarly to those collected at the first sampling date. Soil
samples were taken from the row of the soybean sampled area at the
second sampling date for determination of soil fertility status and
nematode assay. Leaf samples were also taken on this date for
diagnostic purposes.

Cropping System Two

The second cropping system was on an area that had been
planted to winter intercrop of wheat crimson clover for the past
4 years. For the first 3 years crops of forage sorghum and soybean
were summer crops planted in a randomized double cropping study
succeeding the wheat-crimson clover intercrop. In the fourth year
the system was wheat-crimson clover intercrop succeeded by corn or
grain sorghum. For the present year the system was wheat-crimson
clover succeeded by soybean. Soybean were planted directly into
the wheat-crimson clover crop and treated the same as described in
cropping system one.

Soybean in this study showed stunted growth in areas of the
field which upon inspection appeared to be infected with root-knot
nematodes. A randomized complete block comparison of the infected
areas (designated as +) were compared to areas within a few meters
which appeared healthy and normal (designated as -). Four
replications randomized over the field were sampled.








Samples were taken from 1-m2 areas at times and stages of
development described in cropping system one. Samples were
prepared for analysis the same as for cropping system one.
Therefore for both cropping systems, the three treatments were
designated as follows: 1) rye, for those soybean samples taken
after the rye crop, 2) +, for those soybean samples taken from
observed nematode infected areas following crimson clover, and 3) -
for those soybean samples taken from healthy looking areas
following crimson clover.

Plant N Analysis
A 100 mg of plant sample, 3.2 g of salt-catalyst (9:1
K2SO4:CuSO4 ), 2 glass beads and 10 ml of H2SO4 was vortexed in a 100
ml Pyrex test-tube under a hood. To reduce frothing, 2 ml 30% H202
was added in small increments and tubes were digested in an
aluminum block digester at 370 C for 210 minutes (Gallaher, 1975).
Tubes were capped with small funnels which allowed for evolving
gases to escape while preserving refluxing action. Cool digested
solutions were vortexed with approximately 50 ml of deionized
water, allowed to cool to room temperature, brought to 75 ml
volume, transferred to square Nalgene storage bottles (glass beads
were filtered out), sealed, mixed and stored. Nitrogen trapped as
NHSO4, was analyzed on a Technicon AutoAnalyzer II system (manifold
colorimeter) linked to an automatic Technicon Sampler IV (solution
sampler) and an Alpkem Corporation Proportioning Pump III. A plant
standard with a long history of recorded N concentration values was
subjected to the same procedure and used as a check.

Plant Mineral Analysis

A 1.00 g sample was weighed into 50 ml Pyrex beakers, placed
in a muffle furnace at 480 C and ashed for a minimum of four hours.
Cooled beakers containing ashed samples were carefully transferred
to a laboratory hood. Ash was carefully saturated with 10 ml
deionized H20, 2 ml of concentrated Hcl was added and gently boiled
to dryness on a hot plate. The digest procedure results in
precipitation of excessive soluble Si which can interfere with the
analysis of other elements. The water/acid ratio was again added,
brought to a gentle boil on the hot plate and removed so that dried
residue would be in solution. After solutions were cooled to room
temperature they were brought to 100 ml volume for a solution
strength of 0.1 N Hcl. Solutions were analyzed for P by
colorimetry, K by flame emission and Ca, Mg, Cu, Fe, Mn, and Zn by
atomic absorption spectrophotometry.

Soil N Analysis

The procedure was identical to plant analysis except 2.0 g of
soil sample was used without glass beads. Soil particles served
the same purpose as boiling beads. The laboratory plant control
sample also served as a check.








Soil Mineral, Ph and Organic Matter Analysis

Soil samples were extracted by a double acid procedure
(Mehlich, 1954) and analyzed for P, K, Ca, Mg, Cu, Fe Mn and Zn as
described for plant mineral analysis. Soil Ph was determined with
a 1:2 soil solution ratio in H O using a glass electrode. Soil
organic matter (OM) was determined by a modified version of the
Walkley Black method (Walkley, 1947; Allison, 1965).

Nematode Analysis
Soil samples for nematode assay were taken from the rows of
soybean plots that were sampled. Twelve cores 15 to 20 cm deep
were taken with a 2.5 cm sampling tube, placed in plastic bags and
stored at 10 C until processed 2-5 days later. The soil was mixed
and a 100 ml aliquot was processed by sugar flotation -
centrifugation (Jenkins, 1964). Root samples consisting of bulked
roots from five or more plants from each plot were assayed for
galling (Endo, 1959).

RESULTS AND DISCUSSION

As plants grow and reproduce they take up and or accumulate
mineral nutrients to meet the physiological needs of these
processes. Dry matter accumulates as time progresses and the
effects of nematodes become more apparent with age (Table 1). This
study agrees with Melakeberhan et al. (1985) in that plant dry
weight and yield are decreased inversely to numbers of infecting
nematodes. Dry matter yield of soybean varied with plant age,
plant part and previous crop as shown in Table 1. Whole plant
yields were only significantly lower in the treatments heavily
infested with root knot nematodes (+) at 72 days after planting
(DAP), whereas at 104 DAP significant differences developed between
each treatment. The older plants, 104 DAP, clearly expressed
differences in whole plant growth as well as in the leaf and stem
portions of the plants. Soybean with previous crops of rye,
crimson clover moderately infested with root knot (-) and crimson
clover heavily infested with root knot (+) had high, intermediate,
and low dry matter yields, respectively. Differences were not as
pronounced in the pod portions 104 DAP where (+) and (-) were
significantly lower yielders than Rye, nor in the roots where only
(+) had significantly lower yields.

The relative plant nutrient status of soybeans, as determined
by diagnostic specimens (Jones, 1974) was affected by cropping
system and nematodes (Table 2.). Differences occurred among
nutrient concentrations; both sufficient and deficient nutrient
levels for normal physiological processes were found. Diagnostic
leaves taken for concentration sufficiency levels revealed adequate
levels of Mn, Fe and Zn and with no differences among the
treatments. Levels of P also were not different among treatments,
but all were deficient in concentration. Concentration of N








followed progression; high in rye, intermediate in (-) and low in
(+) crimson clover. Levels of N were deficient in both
clover/nematode treatments. Potassium and Cu had significantly
lower levels in the (+) and (-) treatments and displayed deficient
concentration levels across all treatments. Calcium levels were
noted as toxic or excessive in both nematode infested treatments
(Jones, 1974). The Ca levels were different in (+) and rye
treatments but (-) was not different from the other two. Calcium
is known to compensate for deficient K to maintain cation balance
(Melakeberhan et al. 1985; Melakeberhan et al. 1987; Been and
Schomaker, 1986; Rao et al. 1988). Magnesium was present in
highest concentrations in (+), intermediate in (-) and low to the
point of deficiency in the rye. Magnesium concentration increase
is an indicator of nematode "damage" as is observed in these tests
(Melakeberhan et al. 1985)

Table 3 displays nutrient concentrations of soybean plant
parts at the R4 stage of growth as affected by previous
crop/nematode infestation. The stem and leaf portions seemed to be
more affected by the presence of nematodes. High leaf N, and leaf
and pod K concentrations were associated with the treatments having
the lowest nematode infestations. Nitrogen and K concentrations
were also observed to be most detrimentally affected by increasing
nematode infection in earlier studies (Melakeberhan et al.1988; Rao
et al. 1988). Stem P and K was significantly less concentrated in
the crimson clover treatments.

Treatments having high nematode infestations had high
concentrations of leaf Ca and Mg (Table 3). Higher Ca
concentration was probably due to compensation for the deficit of
K as previously discussed. The observed leaf Mg concentration is
contrary to reports by Rao et al. (1988) and by Fatemy and Evans
(1986). Magnesium concentration was found to be higher in the
stems of (+) and (-) than that of rye. Pod Mg was significantly
higher in (-) while (+) and rye concentrations were not different.
The rye treatment had shown a Mg deficiency in the diagnostic leaf
analysis (Jones, 1974). These differences may be attributed to
deficient levels in the soil or other unseen factors.

There were other occurrences (Table 3) where highest levels of
nematodes (+) seemed to result in higher nutrient concentration and
some confirmed previous findings; stem Ca (Been and Schomaker,
1986; Doyle et al. 1987) as well as stem and pod Zn (Melakeberhan
et al. 1987) behaved in that manner. High pod Zn concentration was
in (-) while (+) was not quite as high and not different from the
Rye. Stem Mn was more concentrated in (+) and had intermediate
levels following rye but was not significantly different (P = 0.05)
from either (+) or (-) crimson clover.

Nutrient concentration in the pod and root portions appeared
to be generally unresponsive to treatment. The root portions were
not different in most treatments, except for lower concentrations








in the nematode infested treatments in both K and Fe which was also
observed previously with N and K above. It should be noted that in
previous experiments root K and Fe have both increased and
decreased with nematode infection depending on the crop or batch of
plants (Melakeberhan et al. 1987; Viglierchio, 1987; Rao et al.
1988). There were no differences in concentration among treatments
in stem and pod N and Fe, pod P and leaf Zn. Contradictory
observations have been made in upper plant Zn concentration
(Melakeberhan et al. 1985) (Rao et al. 1988). There were no
differences in Cu in any parts across the treatments nor in leaf
and pod Mn.

The lowest nutrient content on a m2 basis occurred in the
nematode infected treatments and highest content in the "healthy"
rye treatments (Table 4.) Without exception, nutrient content was
highest in every element and every part of the soybean grown after
the rye. Also the leaf and stem portions had the highest content
and would be most valuable for use as a green manure. The leaf and
stem portions of N, P, Ca, the micronutrient Zn and the leaf
portions only in K and Mg had significant differences among each of
the treatments. There are several occurrences where the crimson
clover treatments were not different from each other but were
significantly lower than rye. Those observations were in the stem,
pod and root portions in K and pod portions in N, P, Ca, Mg, and
Zn. Stem and pod portions in Mn and Fe, leaf and stem portions in
Cu responded the same. There were also situations where only the
(+) treatment was significantly lowered in nutrient content. Root
Cu and the leaf portions of Fe and Mg behaved in that manner. Root
content of N, P, Mg, and Fe was significantly lower in (+) crimson
clover, while the (-) treatment was not significantly different
from either of the other treatments. No significant changes in
content were observed among the treatments in the root portions of
Ca, Zn and Mn, nor Cu in pod portions or Mn in the leaf.

The results showing affects of age and previous crop on
nutrient content are contained in Table 5. Generally, nutrient
content significantly increases with age and differs among systems.
In the nutrients N, P, and K date, and treatment affected nutrient
content. At 72 DAP only (+) was significantly lowered in nutrient
content, while at 104 DAP all treatments are significantly
different with (+) having the lowest content, crimson clover (-)
being intermediate and rye having the highest level of content.
The effects of nematodes became more apparent as the soybeans grew
older. Calcium and Mg had a very significant increase in mean
content from 72 to 104 DAP and significant differences among the
treatment means for the two dates, with the lowest content being in
the (+) Crimson Clover. Copper significantly increased in mean
content over time with mean treatment differences as the previous
two. The remaining nutrients behaved differently. Mean Mn content
increased very significantly from the first date to the second but
there were no differences among the treatments. Iron content did
not change over time but mean levels were significantly lower in








(+) while (-) was not statistically different from rye or (T)
crimson clover. However, the numerical differences among
treatments seem quite large. Date and treatment interaction
occurred in Zn. Although there were no differences among
treatments for either sampling date, the increase in content from
72 to 104 DAP is very significant.

For purposes of discussion, Tables 6 and 7 were obtained by
performing calculations using data from Table 5. The nutrients N,
P and K were chosen because both age of plants and treatment have
an effect on the content and because of their major importance in
a complete fertilizer. Evaluating the increase in content from 72
to 104 DAP, the previous crop of rye led to highly superior gains
in nutrient content while the cover crop of crimson clover had
meager gains. These differences are attributed to the infestation
of nematodes in both (+) and (-) treatments. Total contribution of
nutrients at 104 DAP planting again shows that the cover crop of
rye is the superior component for a soybean green manure system.
Assuming that 65 % of the N was available for the following crop as
with Bouldin (1988), approximately 220 kg of N/ha was available
from soybean grown subsequent to a crop of corn. The values
obtained for the rye treatment in N, P and K are superior to any of
the other similar green manures reviewed in this paper while some
of the crimson clover treatments approximate other studies
(Badaruddin and Meyer, 1989; Bruulsema and Christie, 1987; Kulkarni
and Pandey, 1988; Pandey and Pendleton, 1986). Because of the
nematode problems associated with the winter cover crop of crimson
clover, that crop would not be an appropriate component for
inclusion in a cropping system with green manure soybean unless
some form of nematode management was in practice.

There were no significant differences in soil nutrients,
organic matter or Ph among the treatments. (Table 8.) However, it
may be worth noting that N, K, Mn, Fe, and Zn concentration in the
soil increases as "plant health" increases, i.e. rye is highest.
Phosphorus seems higher in (-) as does Ca, and possibly low Mg in
(+) crimson clover.

Root gall ratings were significantly higher in the two
nematode infested treatments, (+) and (-) crimson clover (Table 9).
Only two nematode species have notable variation among the
treatments. Significantly more Ring nematodes were present in the
(+) treatment. Root-knot nematodes were significantly lower in (+)
than in rye, and (-) was not different from (+) or rye but still
had an intermediate number of nematodes.

CONCLUSION

The objectives of this study were to determine the crop
nutrition nematode relationships for soybean in two cropping
system histories and to determine the uptake and content of plant
nutrients in a cover crop of soybean as a green manure for a








succeeding summer corn crop. In keeping with these objectives we
have confirmed previous findings in similar works using different
crops, had some opposing observations as well as added some new
findings in light of the nature in which this study differs.

Plant dry weight and yield decreased inversely with increasing
numbers of infecting nematodes. Two treatments were previously
under winter covercrop of crimson clover: 1. displayed visual
symptoms of nematode damage and was found to contain high numbers
of rootknot nematodes [designated by (+) ] and 2. displaying no
visual nematode damage and roots found had intermediate numbers of
rootknot nematodes [ designated (-) ]. The third treatment,
previously under winter covercrop of rye, displayed no visual
symptoms of nematode damage and had low numbers of rootknot
nematodes [designated rye]. At 104 days after planting whole plant
dry matter yields clearly performed as described above as well as
leaf and stem portions of the plants.

Diagnostic leaves (nutrient concentration) revealed that N was
deficient in both crimson clover treatments and followed the same
trend as did dry matter. Potassium and Cu were lower in the
crimson clover treatments. Calcium levels were noted as toxic or
excessive in the crimson clover which demonstrates compensation for
K deficiency. Magnesium concentration increased as nematode
numbers increased, which is another indicator of nematode damage.

The nutrient concentrations of leaf and stem portions of the
soybean plants at the R4 stage of growth seemed most affected by
the presence of nematodes, whereas pod and root portions were not
as responsive. Leaf concentration of N and K in the leaf and pod
decreased as nematode numbers increased. Stem P and K were lower
following crimson clover. Leaf Ca and Mg increased as nematode
numbers increased. Stem Ca, Mn and stem and pod Zn concentrations
were higher in the (+) treatment.

Nutrient content was the highest in soybeans following rye.
The portions of the soybean with the greatest content of nutrients
were the leaf and stem and thus are the most important for green
manure. Content in leaf and stem portions in N, P, Ca, Zn and the
leaf portions of K and Mg was significantly lowered with each
increase in relative nematode infection.

Nutrient content of the soybeans significantly increased with
age. The effects of nematodes became more apparent as the plants
grew older as content levels significantly decrease with increasing
nematode infection. Content of N, P, and K was affected by both
age and treatment as described above. The content treatment means
of Ca, Mg,and Cu were significantly lowered with increasing numbers
of nematodes. Mean Ca, Mg, Mn, and Cu contents significantly
increased over time.








The soybeans grown after the winter covercrop of rye had
highly superior gains in nutrient content over the life of the crop
when compared with the smaller gains of the soybean following
crimson clover. Total contribution of nutrients was likewise
superior in the soybean following rye. This system is the most
appropriate for incorporation as a green manure to be followed by
soybean based on the observations of this study.

ACKNOWLEDGEMENTS

Partial support of this research came from a grant provided by
the Tennessee Valley Authority, Muscle Sholes, AL. Support of Mr.
J.R. Chichester and Mr. H.C. Palmer are also appreciated.








LITERATURE CITED


Allison, F.E. 1965. Organic Carbon. p. 1367-78. in Methods of Soil
Analysis. Part 2. Black C.A., Evans D.D., White J.L., Ensminger
L.E., and Clark F.E. (eds.). Amer. Soc. Agron., Madison, WI.

Badaruddin, M, and D.W. Meyer. 1989. Forage Legume Effects on Soil
Nitrogen and Grain Yield, and Nitrogen Nutrition of Wheat.
Agron. J. 81:419-24.

Been, T.H., and C.H. Schomaker. 1986. Quantitative Analysis of
Growth, Mineral Composition and Ion Balance of the Potato
cultivar Irene infested with Globodera pallida S. Nematologica.
32:339-55.

Borror, D.J., and R.E. White. 1970. Orthoptera. p. 78. In A
Field Guide to the Insects of America North of Mexico.
Houghton Mifflin Company, Boston.

Bouldin, D.R. 1988. Effect of Green Manure on Soil Organic Matter
Content and Nitrogen Availability. p. 151-63 in Green Manure in
Rice Farming. International Rice Research Inst., P.O. Box 933,
Manila, Philippines.

Bruulsema, T.W, and B.R. Christie. 1987. Nitrogen contribution to
succeeding corn from alfalfa and red clover. Agron. J. 79:96-100.

Doyle, A.D., R.W. McLeod, P.T.W. Wong, S.E. Hetherington, and
R.J. Southwell. 1987. Evidence for the involvement of root lesion
nematode Pratylenchus thornei in wheat yield decline in northern
New South Wales. Aust. J. Exp. Agric. 27:563-70.

Endo, B.Y. 1959. Response of root lesion nematodes Pratylenchus
brachyurus and P. zeae, to various plants and soil types.
Phytopath. 49:417-21.

Fatemy, F., and K. Evans. 1986. Effects of Globodera rotochiensis
and water stress on shoot an root growth and nutrient uptake of
potatoes. Revue. Nematol. 9(2):181-84.

Fehr, W.R., and C.E. Caviness. 1977. Stages of Soybean Development.
S.R. 80 Cooperative Ext. Ser., and Home Econ. Exp. St., Iowa
State University, Ames, IO.

Gallaher, R.N., C.O. Weldon, and J.G. Futral. 1975. An Aluminum
Block Digester for Plant and Soil Analysis. Proc. Soil Sci.
Soc. Amer. 39(4):803-06.

Hiebsch, C. 1990. 1989 Florida Soybean Variety Trials. Agron. Res.
Rep. AY-90-01, Agron. Dept, Inst. Food Agric. Sci., University of
FL., Gainesville.








Jenkins, W.R. 1964. A rapid centrifugal-flotation technique for
separating nematodes from soil. Plant Dis. Rep. 48:692.

Jones, J.B., Jr. 1974. Plant Analysis Handbook for Georgia.
Cooperative Extension Service, Univ. of Georgia College of
Agriculture. Bulletin 735. Athens, GA.

Kulkarni, K.R., and R.K. Pandey. 1988. Annual legumes for food and
green manure in a rice based cropping system. p. 289-99 in Green
Manure in Rice Farming. International Rice Res. Inst., P.O. Box
933, Manila, Philippines.

McSorley, R., and R.N. Gallaher. 1991. Cropping systems for
management of plant-parasitic nematodes. p. 38-45 in Proc. of
Environmentally Sound Agriculture Conf., Bottcher A.B. (ed.). FL
Coop. Ext. Ser., University of FL., Gainesville.

Mehlich, A. 1953. Determination of P, Ca, Mg, K, Na and NH4. N.C.
Soil Test Div. (Mimeo, 1953). N.C. State University,
Raleigh, N.C.

Melakeberhan, H., R.C. Brooke, J.M. Webster, and J.M.D. D'Auria.
1985. The influence of Meloidogyne incognita on the growth,
physiology and nutrient content of Phaseolus vulgaris. Phys.
Plant Path. 26:259-68.

Melakeberhan, H., J.M. Webster, R.C. Brooke, J.M.D. D'Auria, and
M. Cackette. 1987. Effect of Meloidoqyne incognita on plant
nutrient concentration and its' influence on the physiology of
beans. J. Nematol. 11(4):375-80.

Melakeberhan, H., Webster J.M., Brooke R.C., and D'Auria J.M. 1988.
Effect of KNO, on CO2 Exchange Rate, Nutrient Concentration and
Yield of Meloidogyne incognita infected Beans. Revue Nematol.
11(4):391-97.

Pandey, R.K., and J.W. Pendleton. 1986. Soybeans as green manure in
a maize intercropping system. Expl. Agric. 22:179-85.

Rao, Y.S., A. Jayaprakash, and J. Mohanty. 1988. Nutritional
disorders in rice due to infestation by Heterodera oryzicola and
Meloidogyne graminicola. Revue Nematol. 11(4):375-80.

Soil Survey Staff. 1984. Official Series Description of the
Arredondo Series. U.S. Gov. Printing Off., Washington, D.C.

Viglierchio, D.R. 1987. Elemental distribution in tissues of plants
heavily infected with nematodes. Nematologica. 33:433-50.

Walkley, A. 1947. A critical examination of a rapid method for
determining organic carbon in soil. Soil Sci. 65:252-64.








TABLE 1.
Dry matter yield of soybean affected by plant age, plant part and previous crop.

Previous Crop

Date Days after Plant Crimson Crimson Rye
planting Part Clover (+) Clover (-)


---------gm~ ---2..

23 June 72 Whole Plant 187 b 540 a 601 a

30 July 104 Whole Plant 343 c 806 b 1422 a

30 July 104 Leaf 136 c 295 b 449 a

30 July 104 Stem 129 c 332 b 661 a

30 July 104 Pod 32 b 52 b 146 a

30 July 104 Root 47 b 127 a 167 a

(+) Roots heavily infested with root knot nematodes.
(-) Roots moderately to few root knot nematodes.
Values in rows among previous crops not followed by the same letter are significantly
different at the 0.05 level of probability according to LSD tests.







TABLE 2.
Nutrient concentration of upper mature soybean leaves at the R4 stage of growth affected by
previous crop.


------------------Previous Crop-------------------
Nutrient Unit Crimson (+) Crimson (-) Rye
Clover Clover
------------------------------------------- --- === ------ === --------- -------

Nitrogen g kg-1 28.38 c (D) 33.88 b (D) 41.95 a (S)

Phosphorus g kg-1 2.20 a (D) 2.34 a (D) 2.66 a (D)

Potassium g kg-1 3.58 b (D) 4.71 b (D) 11.71 a (D)

Calcium g kg-1 18.10 a (T) 16.10 ab(T) 13.00 b (S)

Magnesium g kg-1 6.06 a (S) 4.89 b (S) 2.68 c (D)

Copper mg kg-1 1.7 b (D) 2.0 b (D) 2.7 a (D)

Manganese mg kg-1 77.7 a (S) 57.7 a (S) 63.8 a (S)

Iron mg kg-1 62.5 a (S) 62.5 a (S) 77.5 a (S)

Zinc mg kg-1 25.8 a (S) 31.0 a (S) 41.0 a (S)
-------------------------------------~~-------------------------------------------------
S = Sufficient; D = Deficient; T = Toxic
Values in rows among previous crops not followed by the same letter are significantly
different at the 0.05 level of probability according to LSD tests.






TABLE 3.
Nutrient concentration of soybean plant parts at the R4 stage of growth affected by previous
crop.

--------------Previous Crop--------------------
Plant Nutrient Unit Crimson (+) Crimson (-) Rye
Part Clover Clover

Leaf Nitrogen g kg-1 29.10 c 35.48 b 40.71 a
Stem Nitrogen g kg-1 14.77 a 17.66 a 13.09 a
Pod Nitrogen g kg-1 26.16 a 21.40 a 32.18 a
Root Nitrogen g kg-1 13.99 a 11.80 a 13.33 a

Leaf Phosphorus g kg-1 2.70 a 2.74 a 2.86 a
Stem Phosphorus g kg-1 2.89 b 3.01 b 3.43 a
Pod Phosphorus g kg-1 3.55 a 3.96 a 3.78 a
Root Phosphorus g kg-1 2.60 a 2.65 a 3.21 a

Leaf Potassium g kg-1 5.97 c 8.55 b 16.40 a
Stem Potassium g kg-1 3.94 b 5.03 b 13.88 a
Pod Potassium g kg-1 9.20 c 14.50 b 19.23 a
Root Potassium g kg-1 3.65 b 4.24 b 7.90 a

Leaf Calcium g kg-1 16.48 a 14.15 b 11.53 c
Stem Calcium g kg-1 8.23 a 6.51 b 5.68 b
Pod Calcium g kg-1 7.34 a 6.81 a 6.27 a
Root Calcium g kg-1 4.73 a 3.66 a 4.01 a

Leaf Magnesium g kg-1 6.13 a 5.12 b 3.52 c
Stem Magnesium g kg-1 5.03 a 4.77 a 3.81 b
Pod Magnesium g kg-1 4.49 b 4.99 a 4.37 b
Root Magnesium g kg-1 3.33 a 3.01 a 3.21 a

Leaf Copper mg kg-1 3.2 a 2.2 a 2.7 a
Stem Copper mg kg-1 2.2 a 1.5 a 2.2 a
Pod Copper mg kg-1 3.0 a 3.7 a 3.7 a
Root Copper mg kg-1 2.7 a 3.2 a 3.0 a








TABLE 3. Continued

-------------------Previous Crop-----------------
Plant Nutrient Unit Crimson (+) Crimsom (-) Rye
Part Clover Clover


Manganese
Manganese
Manganese
Manganese


Iron
Iron
Iron
Iron

Zinc
Zinc
Zinc
Zinc


mg kg-1
mg kg-1
mg kg-1
mg kg-

mg kg-1
mg kg-
mg kg-1
mg kg-

mg kg-1
mg kg-1
mg kg-1
mg kg-1


81.0 a
27.5 a
39.0 a
21.0 a

145.0 a
87.5 a
127.5 a
242.5 b

45.3 a
49.7 a
50.2 ab
33.0 a


Values in rows among previous crops not followed by the same letter are significantly
different at the 0.05 level of probability according to LSD tests.


Leaf
Stem
Pod
Root

Leaf
Stem
Pod
Root

Leaf
Stem
Pod
Root


66.8 a
17.0 b
34.8 a
17.8 a

122.5 a
65.0 a
102.5 a
277.5 b

51.3 a
29.0 b
54.5 a
32.0 a


64.2
20.5
33.8
18.2

110.0
97.5
112.5
350.0


54.0 a
27.5 b
47.3 b
33.7 a








Nutrient


TABLE 4.
content of soybean plant parts at the R4 stage of growth affected by previous crop.


-------------------Previous Crop-----------------
Plant Nutrient Unit Crimsom (+) Crimson (-) Rye
Part Clover Clover
---------------------------------------------------------------------


Leaf
Stem
Pod
Root

Leaf
Stem
Pod
Root

Leaf
Stem
Pod
Root

Leaf
Stem
Pod
Root

Leaf
Stem
Pod
Root

Leaf
Stem
Pod
Root


Nitrogen
Nitrogen
Nitrogen
Nitrogen

Phosphorus
Phosphorus
Phosphorus
Phosphorus

Potassium
Potassium
Potassium
Potassium

Calcium
Calcium
Calcium
Calcium

Magnesium
Magnesium
Magnesium
Magnesium

Copper
Copper
Copper
Copper


-2
g m-2

g m 2
g m-2
gm2
g m-2
-2



g m2
g-2
gm2
g -2
g m 2

gm
gi2
g m-2
g m-2



g m-2
g m-2



g m 2
g -2





g m2
g -2




g m
g m-2








mg m
-2
gm
-2
g m-2
-2
g -2
-2



mg m-2
mg m-2
mg m-2
mg m-2


10.47 b
5.73 b
1.17 b
1.48 ab


3.98 c
1.89 c
0.83 b
0.66 b

0.37 c
0.37 c
0.11 b
0.13 b

0.81 c
0.50 b
0.31 b
0.18 b

2.33 c
1.06 c
0.25 b
0.23 a

0.83 b
0.64 c
0.15 b
0.16 b

0.44 b
0.28 b
0.10 a
0.11 b


0.81
1.00
0.20
0.34

2.52
1.65
0.76
0.55

4.17
2.16
0.37
0.46

1.51
1.58
0.26
0.38

0.67
0.51
0.19
0.42


18.35
8.55
4.67
2.27

1.29
2.26
0.56
0.54

7.32
9.22
2.93
1.35

5.20
3.78
0.86
0.68

1.59
2.52
0.62
0.54

1.20
1.49
0.60
0.50







TABLE 4. Continued

-----------------Previous Crop-------------------
Plant Nutrient Unit Crimson (+) Crimson (-) Rye
Part Clover Clover

-2
Leaf Manganese mg m2 11.32 a 19.80 a 29.25 a
Stem Manganese mg m-2 3.61 b 5.60 b 13.67 a
Pod Manganese mg m-2 1.27 b 1.74 b 4.96 a
-2
Root Manganese mg m2 1.04 a 2.21 a 3.13 a

Leaf Iron mg m-2 20.25 b 36.21 a 49.14 a
Stem Iron mg m-2 11.29 b 21.82 b 58.50 a
Pod Iron mg m-2 3.95 b 5.31 b 16.11 a
Root Iron mg m-2 11.59 b 35.15 ab 59.36 a

Leaf Zinc mg m-2 6.27 c 15.23 b 24.37 a
Stem Zinc mg m-2 6.19 c 9.66 b 18.01 a
Pod Zinc mg m-2 1.60 b 2.80 b 6.90 a
Root Zinc mg m-2 1.62 a 4.07 a 6.00 a

Values in rows among previous crops not followed by the same letter are significantly
different at the 0.05 level of probability according to LSD tests.








Nutrient content of whole soybean


TABLE 5.
plants affected by age and previous crop.


Days -------------Previous Crop--------------
After Nutrient Unit Crimson (+) Crimson (-) Rye System
Planting Clover Clover Mean
-------------------------------------------------------------------


72
104


Means Copper


Nitrogen
Nitrogen

Nitrogen

Phosphorus
Phosphorus

Phosphorus

Potassium
Potassium

Potassium

Calcium
Calcium

Calcium

Magnesium
Magnesium

Magnesium

Copper
Copper


g m-2
g m-2

g m-2

g m-2
g m-2

g m-2
g m-2
g m-2

g m-2

g m-2
g m-2

g m-2

g -2

g m-2
g m-2


mg m-2
mg m-2

mg m-2


4.37 b 13.55 a 14.91 a
7.35 c 18.85 b 33.83 a *
------------------------------------------------------------
5.86 16.70 24.36

0.46 b 1.51 a 1.56 a
0.99 c 2.35 b 4.65 a *
------------------------------------------------------------
0.73 1.93 3.10

0.84 b 5.55 a 8.58 a
1.79 c 5.46 b 20.83 a *

1.31 5.50 14.70

2.19 4.92 5.15
3.76 7.15 10.52
-------------------------- I ,,-----------
2.98 c 6.04 b 7.83 a

1.05 2.30 2.41
1.78 3.73 5.37
------------------------- ---------------
1.42 c 3.01 b 3.84 a

0.61 1.47 2.17
0.92 1.78 3.78

0.76 c 1.63 b 2.98 a


Means


72
104


Means

72
104

Means

72
104

Means

72
104

Means

72
104


10.94
20.01



1.18
2.66



4.99
9.36



4.08
7.15 **



1.92
3.59 **



1.42
1.78 *










TABLE 5. Continued

--------------Previous Crop-----------
Days Nutrient Unit Crimson(+) Crimson (-) Rye System
After Clover Clover Mean
Planting


Manganese
Manganese

Manganese


Iron
Iron

Iron


mg-2
mg m-2
mg -2

mg m
mg m-2

mg -2
mg m
-2
mg m

mg m-2


5.91 17.97 23.46
17.24 29.34 51.00

11.58 a 23.26 a 37.23 a

46.62 150.22 178.33
47.09 98.49 183.11

46.85 b 124.35 ab 543.41 a


15.78
52.27 **



125.06
331.36 ns


72 Zinc-2
72 Zinc mg m2 6.48 a 18.80 a 22.77 a 16.02
104 Zinc mg 2 15.68 a 31.77 a 55.28 a 68.77

Means Zinc mg m-2 11.08 25.28 39.03
-----------------------------------------------------------------------------------------------
* and ** Indicate signicant differences at 0.05 and 0.01 level of probability, respectively,
between the values for the two dates.
ns indicates no significant differences
Values in rows among previous crops not followed by the same letter are significantly
different at the 0.05 level of probability according to LSD tests.


72
104


Means


72
104


Means









Increase in nutrient


TABLE 6.
content of soybean from 72 to 104 days after planting (DAP)


-----------------Previous Crop------------------
Nutrient Unit Crimson (+) Crimson (+) Rye
Clover Clover

Nitrogen kg ha-1 29.8 53.0 189.2

Phosphorus kg ha-1 5.3 8.4 30.9

Potassium kg ha-1 9.5 -0.9 122.5








TABLE 7.
Total nutrient content of whole soybean plants at 104 DAP for use as a green manure

-------------------Previous Crop-----------------
Nutrient Unit Crimson (+) Crimson (-) Rye
Clover Clover

Nitrogen kg ha-1 73.5 188.5 338.3

Phosphorus kg ha-1 9.9 23.5 46.5

Potassium kg ha-1 17.9 54.6 208.3







TABLE 8.
Mehleich I extractible soil nutrients, Kjeldahl nitrogen, organic matter and pH of soil
affected by present crop and previous cropping history.

------------------Previous Crop------------------
Nutrient Unit Crimson (+) Crimson (+) Rye
Clover Clover

Nitrogen g kg-1 0.34 a 0.36 a 0.58 a

Phosphorus mg kg-1 49.6 a 63.6 a 56.0 a

Potasssium mg kg-1 12.4 a 18.0 a 27.6 a

Calcium mg kg-1 335.2 a 426.8 a 261.6 a

Magnesium mg kg-1 33.6 a 47.2 a 48.4 a

Copper mg kg-1 0.16 a 0.16 a 0.20 a

Manganese mg kg-1 2.36 a 2.92 a 3.36 a

Iron mg kg-1 7.72 a 8.92 a 9.92 a

Zinc mg kg-1 1.28 a 1.48 a 1.64 a

O.M. Percent 1.05 a 1.25 a 1.15 a

pH -log[H] 6.6 a 6.6 a 6.4 a

Values in rows among previous crops not followed by the same letter are significantly
different at the 0.05 level of probability according to LSD tests. O.M. = organic matter.







TABLE 9.
Root gall ratings of root knot nematode and numbers of lesion, stubby root, ring and root
knot nematodes per 500 ml soil aliquot as affected by previous crop.

------------------------Previous Crop--------------------
Rating / Crimson (+) Crimson (-) Rye
Nematode Clover Clover

Gall Rating 4.5 a 3.0 a 1.0 b

Lesion Pratylenchus brachyrus 46.0 a 106.5 a 63.5 a

S.R. Paratrichodorus minor 8.0 a 8.5 a 14.0 a

Ring Criconemella spp. 170.5 a 23.5 b 28.0 b

Root Knot Meloidogyne incognita 842.0 a 432.5 ab 81.5 b

Values in rows among previous crops not followed by the same letter are significantly
different at the 0.05 level of probability according to LSD tests. (LSD test was performed
on log transformed data). S.R. = stubby root.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs