Soil organic carbon sequestration as affected by tillage, crop residue, and nitrogen application in rice–wheat rotation system

Abstract

Despite being a major domain of global food supply, rice-wheat cropping system is questioned for its contribution to carbon flux. Enhancing the organic carbon pool in this system is therefore necessary to reduce environmental degradation and maintain agricultural productivity. A field experiment (November 2002-March 2006 evaluated the effects of soil management practices such as tillage, crop residue, and timing of nitrogen (N) application on soil organic carbon (SOC) sequestration in the lowland of Chitwan Valley of Nepal. Rice (Oryza sativa L.) and wheat (Triticum aestivum L.) were grown in rotation adding 12 Mg ha -1 y -1 of field-dried residue. Mung-bean (Vigna radiata L.) was grown as a cover crop between the wheat and the rice. Timing of N application based on leaf color chart method was compared with recommended method of N application. At the end of the experiment SOC sequestration was quantified for five depths within 50 cm of soil profile. The difference in SOC sequestration between methods of N application was not apparent. However, soils sequestered significantly higher amount of SOC in the whole profile (0-50 cm soil depth) with more pronounced effect seen at 0-15 cm soil depth under no-tillage as compared with the SOC under conventional tillage. Crop residues added to no-tillage soils outperformed other treatment interactions. It is concluded that a rice-wheat system would serve as a greater sink of organic carbon with residue application under no-tillage system than with or without residue application when compared to the conventional tillage system in this condition.

The Effect of Crop Residues on Soil Nitrogen Dynamics and Wheat Yield

“…Although the C:N ratio has long been known to be a major factor in controlling the rate from which N is released from crop residues [1,35], in the present study, mineralized soil N was poorly correlated with the residue's C:N ratio (r = 0.05). Models that simulate agronomic scenarios [36][37][38] often describe the biochemical quality of crop residues only by their relative C to N contents (C:N ratio). Indeed, the most common criterion of quality used to predict mass loss or N mineralization during the decomposition of crop residues is the C:N ratio of the plant material [39].…”

“…Therefore, management of a crop residue can contribute to increased nutrient cycling and greater crop yields [4, 6,7] and also has an important role in reducing soil erosion and maintaining yield [8]. By selecting crop rotation and/or management practices such as minimum tillage to reduce soil disturbance and/or increase the amount of residue returned to the soil, soil organic carbon and nitrogen can be increased in the system [6,8,9]. The rate of decomposition and N mineralization increases by increasing the quality of a plant residue [10,11].…”

Climate trends and impacts on crop production in the Koshi River basin of Nepal

“…Typical growing seasons (rounded to whole month) and growth stages for rice, maize and wheat in the region were taken from the relevant literature (Ghimire et al 2011;Paudyal et al 2001;Nayava et al 2009). The growing season months used here are July to November for rice, March to August for maize and November to April for wheat.…”

Daycent Simulation of Methane Emissions, Grain Yield, and Soil Organic Carbon in a Subtropical Paddy Rice System

“…In this anoxic soil environment, physical protection of SOM in soil aggregates is less effective in stabilizing SOM than in aerobic soils, possibly by the effect of water decreasing aggregate stability during the flooded rice growing season (Nascimento et al, 2009). Consequently, SOC is increased to a very small extent, if any, by the adoption of no-tillage in irrigated rice fields (Nascimento et al, 2009;Rosa et al, 2011;Ghimire et al, 2012;Das et al, 2014;Huang et al, 2016).…”