Field Research Brief No. 14
TITLE: 1502. Phosphorous Rates and Methods of Application
RESEARCHERS: Mike Wade and Djoko Santoso
OBJECT I VES:
1. Determine optimum rates of F' fertilizer on a
newly cleared soil (Paleudult),
2. Determine cost:benefit ratio of various methods
of applying TSP fertilizer,
3. Study the long term 'effects of various P
management (rates and methods) on crop
production and soil P levels,
4. Determine critical P soil test values for rice
SOIL: Paleudult, LCeak; located in Sitiung Vc, forest cleared in
82/83 wet season, experiment initiated in December, 1983.
TREATMENTS:- Randomized Complete Block with 3 replications, 4X6m
1. no P
2. 20 kg P broadcast
3. 40 kg P
4. 80 kg F'
5. 20 kg F' banded-
6. 40 kg P
7. 80 kg P
8. 20 kg P in dibble hole
beside seed hole
9. 20 kg P in seed hole
10. 20 kg P banded between
every other row
11. 80 kg P broadcast plus
2T lime, 50 kg K, 100 kg
MgSO4 per hectare
Treatments 1-10 receives no base fertilizer, just P as
indicated. Lime, Ca(OH)2, is applied as a surface
broadcast at 325 kg/ha over the peanut rows after
planting as a Ca source.
The P treatments were applied at the rates indi-
cated on both of the first two crops, peanuts and mung
beans. Soil analysis indicated a build-up of P in all
but the zero plots. Therefore the third and fourth
crops, rice and peanuts, were grown on the residual
treatments, i.e. no new P was applied to either crop.
CROP: This report covers the fourth crop in the experiment,
peanuts. A local variety of valencia-type peanut was planted in
a 25 X 25cm pattern with 2 seeds per dibble hole in February,
1985. No pesticides were used and no serious pests were evident.
No fertilizer applications were made except for treatment 11 as
per plan. A blanket application of 325 kg Ca(OH)2/ha was broad-
cast over the row after planting. A lack of rainfall prior to
and after planting resulted in an erratic stand. Because of the
poor rainfall distribut:i. on that had been experi enced thrul-ugj hoc ut
the 84/85 rainy season, a replant was not done as an even worse
population may have resulted. Analysis of covariance was done'
with yields and plant population to provide adjusted yield
means accounting for population differences. These adjusted
yields are used in the data presentation and results.
RESULTS: Figure 1 shows that the residual of the broadcast
applications tended to give better yields than the residual of
the barded applications, although they were not significantly
different (P.05). Broadcast applications should provide a
more uniform residual for subsequent crops than banding, although
between crop tillage would tend to spread the residual band.
There was very little difference among the five application
methods at the 20kg rate. The-method with the most limited
distribution (banding every other row) gave the lowest yield but
again only slightly less than the others and not statistically
Perhaps the most noteworthy aspect of this harvest is how
the response curve compares to the first peanut harvest (1984) as
illustrated in Fig 2. The response is much less dramatic this
year as the zero and 20 kg/ha rates yielded relatively well coiiparri:
to 1984. This is opposite of what one might expect as conventio-
nal wisdom would predict the response to increase over time not
decrease. However in this experiment a re-application of the
indicated rates was made to the second crop, mungbeans.
Thus the '85 peanuts were growing under the residual of two appli-
cations of the P rates. In fact Figure 3 shows extractable P to
be several ppm higher for all rates after this harvest than after
the first harvest (and first P applications). This is understan-
dable except for the zero plot which has not had any P fertilizer
applied at any point in the experiment. Figure 4 shows very
sharp yield increases related to only modest increases in ext. P.
Thus the slight increase in P even at the zero rate could explain
why those plots did so much better in '85 than in '84. But then
the question remains why did the zero plots increase in available
or extractable P, albeit only a few ppm?
Other work at Sitiung has shown remarkable responses to
green manuring and crop residue recycling. The previous crop was
upland rice that produced phenomenal amounts of biomass (10
t/ha, FRB #3), which was returned to the plots as is the manage-
ment practice for this experiment. Even the zero plots produced
straw on the order of 2.5 t/ha, which may be enough to positively
influence available nutrients including P. Green manuring appar-
ently did just that in an experiment in Sitiung II (FRB #2).
This experiment is indicating that the question of
maintaining fertility after clearing, at least for low input
systems, may be a simpler process than is generally thought.
Table 1 shows that both P and acid saturation levels (mean of all
plots) are so far remaining quite stable over time. P
applications were made only before the first and second crops,
and 325 kg burned lime/ha have been topdressed at planting of
each of the legumes, i.e. 3 X. As mentioned all residues are
returned to the plots. These are very modest rates and simple
management practices but appear to be adequate. This is
evidenced by the fact that trt 11, which had 80 kg P/ha, a base
application of 2t lime/ha at the initiation of the experiment (as
well as the topdresses) and a per crop application of K and Mg,
has not out yielded trts 4 and 7 which had only the 80 kg P rate
and topdressed lime. On the other hand, admittedly yields have
been consistently low and may not be a good indicator of
fertility. However we feel that the low yields have behre due to
non-fertility factors. Soil analysis would indicate that iridted
a reasonable fertility level is being maintained. Hopefully
succeeding crops will give a better indication of the t.r.e [Lovel
of productivity being mai ntained by this low input management
Extractable P and acid saturation (mean of all plots)
after each crop harvest during this experiment.
Ac i d
Yi -e uk
..*'i I ; ': j : i ..I' '- "
Irt~.&t-.* ~' 2
D ;:111 rr-e
i :.....~ ~~~~ i
i sa ko
.i :r i ~/
?~ i. /It
.u;:i! ~Y r
'1 C I
T~I i i~ c
i i f I I a~ ~r t. ,
-fI-M--1 ~-~-IIc~ -":-~tt.fl~ ri 7
~... .... :! ~" 'i '" "
i :1! i:ii
:::-:::::i:;: ~;i~::.: ::;:;:i~:!l:ii tfii I;i ittf !''' :i i
::I 'ii; i
Ii i i i i r i I : 11!!1 iB;/i r i' ; : : : i : i : : 1
,.....,, ::i .. r... '.
~ I':'' r I
-11-: j L:l r: I~ :.... ~ j'
"i]i Ilii :r : :
:tr i ..:. : I
: : 1:::::::::::I.'~ : : :
-I---i U11,:: i,:!--!.....i ;
: ;i: !: r : ; 1i i; : r
:;1::::! i.: i i.
iTT:; : 1 i i j : I i :
.... I :I
i ij i i : i j i ; i i j i I I : I j ~iL.f i i
::: ri iii~
... ;iii 'il i;
i: i: : ~:: : I
::::: : : : : I
:r'T ::: i!
I ia i ;1 f i : i-i iI : i
-: :: i: I~ : : 1
--~ i;- ii ::::T ; : : i: i i
... :. .:li i i. ::ii ii: ::::' ill
i ; : I;-~hn'I i i i j I I Iiit i
I ; : : i i 1111 i j i ; I r I i i i i i i I r r : !
I i :: .f
: : I I:
I 'I:" li!(~
ii!I ::j'ii i i 1I:-in i i i: : 1: r i I I:; I
""' i ; t
I ; ,
--~ --~I ~tti ': '
i.: :; 11 I~1;~~I
'''~' .11.1. .91 'iitr3 : g i
...., ..~..; ;r I i ': t '
i Ii ;; i
ii~c-~, i : ii!ilii; ; 1
: t ; ?1':
1----.--r---+l------ -:: i-:~!~
:::::I:::: :; i ::!i!iilili![:.. Y:nr.d+;
....,.,..:I:: : :: .... :;i:y :::J cYSr~i i f : J1~.
*I'-!tt~t, ijii i-t / f i fiij f 1 i : ;i/ 1 i f tt1: i i: illfrllT
I~II i I
:il: I : ~
i 1 ij[ ~ i! I 1 ;::: i'
t 1: i I : 1--1 I I i,
)~:I-i'.~..' IZ (ri; ~1~ II
/48~- qb5lie(igi~~ JrY~ Pa
1~~~ ~ ~ .I4 .a? :il .i;iii;;i .
ii L Ot- /f ilii :.
~PIL' :hHr :