Nitrogen and phosphorus transformations as affected by crop residue management practices and their influence on crop yield

Abstract

A 15-year field experiment investigated crop residue management practices, with crop residue removal, burning and incorporation as the main treatments and nitrogen levels as subtreatments. The effects of crop residue management practices on rice and wheat yield were measured for 11 years. Surface soil samples were taken to study nitrogen and phosphorus immobilization/adsorption and their release under laboratory conditions. The field experiment indicated that residue burning and residue removal resulted in greater grain yields of rice (5.57 and 5.53 t/ha, respectively) and wheat (4.12 and 4.02 t/ha, respectively) than residue incorporation (4.5 1 t/ha rice and 3.72 t/ha wheat). Laboratory experiments indicated that by the addition of crop residues nitrogen and phosphorus were converted to unavailable forms through immobilizaoron and adsorption, respectively.Crop residue management practices were discontinued after 13 years and wheat and maize crops were grown in sequence. There were significantly greater yields of wheat (3.57 t/ha in 1992-93 and 3.6 t/ha in 1993-94) and of maize (2.1 tl'ha in 1993) in plots where the residues had previously been incorporated than where the residues were previously either removed or burned. This is attributed to release of nitrogen and phosphorus from the incorporated residues.

Effects of straw retention and phosphorous fertilizer application on available phosphorus content in the soil solution during rice growth

“…Other studies have shown that straw retention has no significant effect on the available P in soil (Malhi et al 2011;Prasad et al 1999;Yadvinder et al 2008). Beri et al (1995) observed a decrease in the available P content in soil after 11 consecutive years of straw retention in an Indian ricewheat rotation cropping area. In the same area, Bhandari et al (2002) reported that the available P in soil decreased significantly after 10 consecutive years of straw retention after the rice season.…”

“…Beri et al (1995) also claimed that when straw with high ratios of C:P was mixed with soil, the straw enhanced P adsorption in the soil within the same growth season (McGill and Cole 1981;Murrmann and Peech 1969;Medley et al 1982). Microbial activity has been shown to play a major role in redistributing P into different forms in the soil, and straw retention has been shown to affect the balance of P in the soil (McGill and Cole 1981;Murrmann and Peech 1969).…”

“…Studies have been conducted to investigate the relationship between straw retention, available P content in the soil solution and yield (Beri et al 1995;Gupta et al 2007;Lan et al 2012;McLaughlin et al 1988;Pathak et al 2006;Yadvinder et al 2004), and the results showed that straw retention had a significant impact on the available P content in the soil solution and rice yield, although the results were not consistent. In this study, straw retention had no significant impact on yield; however, the test results should be verified in experiments conducted over longer time periods.…”

“…The orthophosphate taken up by crops originates from the soil solution and solid phase of various inorganic and organic P fractions (Negassa and Leinweber 2009). The practice of straw retention has been reported to affect available P concentrations in the soil and, consequently, crop yield (Beri et al 1995;Gupta et al 2007;Lan et al 2012;Pathak et al 2006;Yadvinder et al 2004). Biological and biochemical reactions, such as mineralization and dissolution by phosphatase enzymes, control much of the organic P fractions (McGill and Cole 1981;Murrmann and Peech 1969;Medley et al 1982), and microbial activity has been shown to play a major role in redistributing P into different forms in the soil.…”

Microorganisms in the Conversion of Agricultural Wastes to Compost

“…Besides, it involves additional cost of labour, irrigation and extra tillage [4]. Moreover, observations of long term experiments indicate that though incorporation of agro-residues in soil improves soil health significantly [5][6][7], it decreases the subsequent crop yields due to production of microbial phytotoxins and allelochemicals [8] and immobilization of the available nitrogen [9]. Incorporation of agro-residues like paddy straw increases the CH 4 emission from field [10,11] especially in irrigated soils, which in turn adds to the malice of global warming.…”