Substitution of nitrogen requirement of maize through leaf biomass of Leucaena leucocephala: agronomic and economic considerations

Abstract

In a 3-year field study, the effects of substitution of nitrogen requirement of maize through Leucaena leaves were studied on runoff, soil loss, maize and wheat yield and economic returns. The treatments were (1) 80 kg N ha -1 all through Leucaena leaves (80 L), (2) 40 kg N through Leucaena leaves + 40 kg N ha -1 through fertilizer (40 L + 40 F), (3) 20 kg N through Leucaena leaves + 60 kg N ha -1 through fertilizer (20 L + 60 F), (4) 80 kg N ha -1 all through fertilizer (80 F), and (5) control (No fertilizer). Green Leucaena leaf biomass (containing 3.3% N on dry basis) was incorporated every year in 15 cm top soil two weeks before sowing of summer maize.

Green leaf manuring with prunings of Leucaena leucocephala for nitrogen economy and improved productivity of maize (Zea mays)–wheat (Triticum aestivum) cropping system

“…In a pot culture study, Mafongoya et al (1997) did not find response to N fertilizer when Leucaena prunings at 3-6 t ha -1 were incorporated, indicating adequate N supply from the prunings. In this study, the dried and ground Leucaena prunings were incorporated, which resulted in enhanced mineralization of N. However, in our study, applying less than half of total N through urea decreased the yield of maize significantly probably due to temporary immobilization of N and thereby less N availability in soil at higher proportions of Leucaena N. Several workers have reported that 50-75% of N requirement of maize can be substituted through Leucaena prunings under varying soil and climatic conditions (Mittal et al 1992;Palled et al 2000;Lehria et al 2006). There are also reports on higher production of maize with combined use of Leucaena and N fertilizer than with N fertilizer alone (Mittal et al 1992;Pandey et al 1998;Palled et al 2000;Soltan et al 2001) probably due to gradual and controlled release of N synchronizing with crop demand at different stages.…”

“…Further, maize being more nutrient exhaustive than wheat, required ample supply of easily available N for its optimum growth which was more from urea fertilizer than from Leucaena prunings. Mittal et al (1992) found that maize yields obtained from 100% Leucaena or urea N treatments were similar, and were even more in Leucaena plots in the third year. However in our study, prunings from Leucaena alone could not provide the maize crop with adequate N supply, despite higher temperatures and ample soil moisture, which were conducive for decomposition of Leucaena biomass.…”

“…However, in the second cycle, when the soil fertility had improved due to the cumulative effects of Leucaena application over the past three seasons, the yields stabilized with equal proportions of Leucaena and urea N. Shah and Ahmed (2006) reported that the highest yield of wheat was obtained from treatments receiving N from urea and FYM in 75:25 ratio, followed by the 50:50 ratio; and the yields were significantly lower in treatments where N from urea source was below 50%. Significant residual effects of Leucaena applied to maize on following wheat have been obtained (Mittal et al 1992;Nanda et al 2002;Lehria et al 2006).…”

“…This was because urea N increased the productivity more than Leucaena N and the cost of Leucaena N was about twice (Rs 20 kg -1 N) more than urea N (Rs 11 kg -1 N). Mittal et al (1992) reported significantly higher net returns when Leucaena and urea N were applied in 25:75 proportion in maize-wheat system. In our economic analysis, we considered only the direct cost of N and not the indirect benefits of Leucaena green leaf manuring.…”

Moisture conservation and nitrogen recycling through legume mulching in rainfed maize (Zea mays)–wheat (Triticum aestivum) cropping system

“…Use of Leucaena prunings as fodder has not found much favour with the farmers due to the presence of momisine toxin, particularly in the rainy season, but it can be used as mulch because of succulent biomass rich in N (3-5%) and low C:N ratio (Karachi 1998). Mulching or incorporation of tender twigs of Leucaena has been found beneficial for moisture conservation and meeting N requirement of maize (Mittal et al 1992;Mafongoya et al 1997;Soltan et al 2001), with significant residual effects on soil fertility and productivity of following crops (Mureithi et al 1994;Jones et al 1996;Lehria et al 2006). In view of the growing crisis for energy, water and chemical fertilizers, and non-availability of conventional organic materials for recycling in crop production, it is important to produce and recycle vegetative materials in situ along with the main crop.…”