The A S interactions on millet DM and N uptake were due to response differences

The a s interactions on millet dm and n uptake were

This preview shows page 4 - 7 out of 12 pages.

The A × S interactions on millet DM and N uptake were due to response differences in pots containing 2262.tex; 9/06/1999; 14:02; p.4
Image of page 4
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% 2262.tex; 9/06/1999; 14:02; p.5
Image of page 5
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.
Image of page 6
Image of page 7

You've reached the end of your free preview.

Want to read all 12 pages?

  • Spring '08
  • Unknown
  • pg, NS

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture