Nitrogen Dynamics and Crop Growth on an Alfisol and a Vertisol under Rainfed Lowland Rice-based Cropping System
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Date
2000
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Abstract
Crop rotation experiments were conducted over 2 years to quantify N supply-demand under rainfed lowland rice±chickpea and rice±fallow cropping systems on a loam Al®sol and a clay Vertisol in India. Signi®cant differences among N rates (0, 40, 80, and 120 kg N haÿ1 ) and soils were observed with rice for grain yield, total biomass and grain N uptake in both years. Low N response, low grain yield, low N uptake, and a short grain ®lling phase during the 1995 wet season was due to post-heading water stress. The stress was more pronounced on the Vertisol and at high N rates. This resulted in lower N content at maturity than at heading. The loss of biomass N from plant implied that apparent N recovery (AR) and physiological nitrogen use ef®ciency (PNUE) may differ signi®cantly based on whether maximum N accumulation or total N uptake at maturity was used. Plant N recovery, both by the N difference method and 15N technique, revealed much lower recovery of fertilizer N (21± 27%) with rainfed lowland rice than with irrigated dry-season rice. The residual effect of N applied to the preceding rice crop was nonsigni®cant on all yield, growth, and N uptake parameters of chickpea. The performance of chickpea was better on the Al®sol than the Vertisol, principally due to soil physical attributes. The better performance and longer growth duration during 1994±1995 dry season as opposed to the 1995±1996 season was attributed to higher rainfall (92 mm versus 39 mm) and rainfall during the critical pod-®lling to maturity phase. Mineralization and nitri®cation of N was negligible during the rice± fallow period due to the dry conditions and low organic matter content. This was corroborated by the similarities in N balance between rice±chickpea and rice±fallow system. The PNUE of rice was 33 to 57 kg grain per kg N absorbed compared with 25 to 27 kg grain per kg N absorbed of chickpea, owing mostly to higher N concentration of chickpea grain and the higher energy cost due to biological N fixation.
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Keywords
Vertisols, Chickpeas, Rice
Citation
Patil, S.K., U. Singh, V.P. Singh, V.N. Mishra,R.O. Das and J. Henao. 2001. “Nitrogen Dynamics and Crop Growth on an Alfisol and a Vertisol Under a Direct-Seeded Rainfed Lowland Rice-Based System,” Field Crops Research, 70:185-199.