The a s interactions on millet dm and n uptake were

The A × S interactions on millet DM and N uptake
were due to response differences in pots containing
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219
Table 2. F ratios for treatment effects on cumulative millet DM, N and P uptake, and soil properties
Source of DM N uptake P uptake Total Soil Bray1- Total Heavy N heavy P heavy N light P light
variation (g pot
- 1
) (mg pot
- 1
) (mg pot
- 1
) soil-N NH
4
–N P SOM SOM SOM SOM SOM SOM
(mg kg
- 1
) (mg kg
- 1
) (mg kg
- 1
) (mg kg
- 1
) (g pot
- 1
) (mg pot
- 1
) (mg pot
- 1
) (g kg
- 1
) (g kg
- 1
)
Species (S) 19.3 21.9 2.4 4.3 NS NS NS 45.0 41.3 0.3 1.8 3.5
Amendment (A) 6.1 9.6 69.1 9.3 NS 24.1 NS 4.3 284 136 8.2 146
Fertilizer-N (N) 374 585 38.0 18.1 NS NS 4.5 NS 30.8 NS NS NS
S
×
A 9.1 16.4 4.3 3.7 NS NS NS 27.0 2.9 NS NS NS
S × N 3.1 2.6 NS NS NS NS NS NS NS 5.6 NS NS
A × N NS NS NS 5.0 NS NS NS NS 19.7 NS 19.5 NS
S
×
A
×
N NS 2.5 NS NS NS NS NS NS NS NS NS 3.5
MSE 5.69 602 66.1 81.5 0.90 0.20 0.23 2.01 15.4 0.10 1.11 0.01
Figure 1. Cumulative dry matter production by millet
the leaves of PG and VU. Whereas the feces derived
from all plant species, on average, produced similar
amounts of DM and N uptake over the 4 crop cycles,
pots containing the leaves of PG produced less DM
and had lower N uptake than pots containing the leaves
of VU (Figures 1 and 2).
Total-P uptake by millet was most affected by
amendment type followed by fertilizer-N (Table 2).
The effect of amendment type on millet P uptake de-
pended to some extent on plant specie (i.e. relatively
low F ratio for S × A interaction). On average, mil-
let in pots containing feces accumulated about 37%
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220
Figure 2. Cumulative N uptake by millet
more P than those amended with leaves. Addition of
leaves generally reduced millet-P uptake relative to the
control (Figure 3). Millet grown in pots containing the
leaves of GS, PE and PG had less ( P < 0.05) P uptake
than millet grown in control pots. Whereas addition
of most leaves apparently immobilized P, addition of
feces derived from PE, GS and VU, increased ( P <
0.05) P uptake by millet.
Relationships between amendment composition and
yield and nutrient uptake
The amounts of leaf DM and cell wall (NDF) added
to pots, and the NDF:N ratio of the leaves added to
pots accounted for about 60% (i.e. single correlation
coefficients squared) of the variation in cumulative
millet DM yield and N and P uptake (Table 3). In
pots that received fertilizer-N, the negative effects of
these leaf additions were most pronounced during the
first millet growing cycle, and diminished thereafter.
The opposite response trend was observed in pots that
did not receive fertilizer-N: the negative effects of leaf
DM, NDF and NDF:N application became more pro-
nounced during the 2nd, 3rd and 4th millet growing
cycles. Millet DM and N uptake was positively related
to the total N concentration of leaves. Fractionation of
total-N into soluble- and insoluble-N did not improve
prediction of millet DM and N uptake over predic-
tions using total-N as a dependent variable. Neither
leaf lignin, polyphenol, nor IPAC (or their ratios with
N) proved to be related to millet response to either
leaf or feces additions, in the presence or absence of
fertilizer-N.