Impact of variable quality organic matter and nitrogen levels on rice wheat productivity, nutrient availability and soil carbon accretion

Raagjeet Kaur

Impact of variable quality organic matter and nitrogen levels on rice wheat productivity, nutrient availability and soil carbon accretion

Date

2024

Authors

Raagjeet Kaur

Publisher

Punjab Agricultural University

Abstract

In recent years, the intensification of the irrigated rice wheat (R W) system has led to the generation of substantial quantities of crop residues, particularly rice straw. On farm rice straw burning is the most widespread method to manage the surplus crop residue among the Indian farmers due to time constraints for wheat sowing, insufficient farm mechanization and low acceptability of paddy straw as fodder. This practice contributes to environmental pollution, health concerns, and loss of nutrients. To tackle these issues, there is an urgent need for the adoption of appropriate Rice Residue Management Practices (RRMPs). In addition, excessive use of nitrogen (N) fertilizers in rice wheat system has resulted in environmental issues like soil and water pollution, greenhouse gas emissions, and soil health degradation. To address these problems, adoption of integrated nutrient management could be an option. Therefore, a long term field experiment (8 years) was conducted to understand how different RRMPs and N fertilizer rates interact to influence R W productivity and soil functions. The treatments consisted of five RRMPs comprising of rice straw removal (RR), rice straw incorporation at the rate 6 t ha 1 (RI), Rice straw burning (RB), Rice straw biochar applied at 2 t ha 1 (RBC1) and 4 t ha 1 (RBC2) in the main plot and five N levels i.e. N0 (0 kg N ha 1), N1 (60 kg N ha 1), N2 (90 kg N ha 1), N3 (120 kg N ha 1) and N4 (150 kg N ha 1) in the sub plots. Results showed that RI, RBC1 and RBC2 plots significantly increased mean wheat and rice grain yield by 4 11%, compared with the RR plots at different rates of N fertilization. The RI, RBC1 and RBC2 plots receiving N2 level of fertilization showed statistically comparable or even higher mean wheat & rice grain yield, in comparison with RR plots receiving N3 level of N fertilizer. Among all RRMPs, RBC2 recorded the maximum wheat & rice productivity, emphasising its potential as an effective agricultural amendment for maximizing crop performance. The RI, RBC1 and RBC2 plots significantly enhanced the nutrient availability in the soil profile, particularly the N forms, ensuring a consistent nutrient supply to the plants. Biochar and straw incorporation positively impacted the physical properties of the soil by reducing bulk density, increasing water holding capacity, and promoting the formation of aggregates and subsequently carbon (C) stabilization within aggregates as well as enhanced the microbial activity in the soil. Greater soil organic C, total C stocks and lesser C dioxide emissions in the biochar amended plots compared with other RRMPs indicates that it can be successfully used for C accretion under R W system. Key findings emphasized the superiority of biochar application and residue incorporation over the conventional practices, even at lower N rates. The outcomes suggested that biochar and residue incorporation offered a viable pathway for achieving both crop productivity and soil health in a resource efficient and environmentally sustainable manner.

Citation

Raagjeet Kaur (2024). Impact of variable quality organic matter and nitrogen levels on rice wheat productivity, nutrient availability and soil carbon accretion (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.