Abstract
Fertilizer-N application and straw incorporation impacts crop productivity due to changes in total organic carbon (TOC), its labile pools and the soil enzymatic activity. A field experiment was established (in 2010) to study the effect of fertilizer-N application (0, 90, 120 and 150 kg N ha-1) and rice straw (RS) incorporation (0, 5.0, 7.5 and 10 Mg ha-1) on crop yield, C input, TOC and its labile pools and soil enzymatic activity under rice (Oryza sativa L.) - wheat (Triticum aestivum L.) cropping system (RWCS) in north-western India. Data showed that fertilizer-N application and RS incorporation significantly (p<0.05) increased the rice and wheat grain yield, compared with control (CK). However, the RS incorporation alone did not impact crop yields. The sustainable yield index (SYI) for wheat was significantly lower with RS incorporation alone as compared with the other treatments. For rice, SYI was significantly higher for RS7.5N120, and was non-significant compared with the RS10.0N120. Annual total C input in soil plough layer (0-15 cm) under RWCS varied between 3.34 and 9.78 Mg C ha-1, which was higher by 4.4 Mg C ha 1 yr-1 (~2.3-times) in RS10.0, compared with CK. The conjoint application of fertilizer-N and RS incorporation (RS10.0N150) significantly increased the TOC, water extractable organic C (WEOC), hot water C (HWC), microbial biomass C (MBC) and basal soil respiration (BSR) due to increased soil enzymatic activity viz. dehydrogenase activity (DHA), fluorescein diacetate (FDA) and alkaline phosphatise (Alk-P). A significant increase in potassium permanganate oxidizable C (KMnO4-C) with RS incorporation under RS10.0N150 increased the C management index (CMI), and hence the soil quality. The inter-correlations between highly weighted soil variables among different principle components (PCs) revealed that KMnO4-C in PC1, FDA activity in PC2, and BSR in PC3 with the highest correlation were the sensitive indicators for assessing soil quality in a RWCS.
Highlights
Rice-wheat cropping system (RWCS) occupies ∼10 million ha (M ha) in Indian Indo-Gangetic Plains (IGPs) (Saharawat et al, 2012) that has been a lifeline for millions of food producers and consumers contributing ∼85% toward country’s cereal production (Timsina and Connor, 2001)
Our results showed that rice straw (RS) incorporation resulted in a significant increase in rice grain yield by 18.8% and wheat grain yield by ∼3.8%, compared with no-straw incorporation
Our results showed that RS incorporation (RS10.0) resulted in increased enzyme activities (DHA, fluorescein diacetate (FDA), and alkaline phosphatise (Alk-P)), which was linked to the increased C input, root exudates containing C rich substrate such as organic acids and carbohydrates (Sharma et al, 2019a,b)
Summary
Rice-wheat cropping system (RWCS) occupies ∼10 million ha (M ha) in Indian Indo-Gangetic Plains (IGPs) (Saharawat et al, 2012) that has been a lifeline for millions of food producers and consumers contributing ∼85% toward country’s cereal production (Timsina and Connor, 2001). The RWCS has successfully maintained the balance between food grain supply and human population growth. This has become possible with the development of high yielding varieties of rice and wheat, availability of chemical fertilizers at the cheap prices, extension in irrigation network and farm mechanization, besides expansion of arable area. The TOC is the most important component in maintaining soil quality due to its role in improving physical, chemical and biological properties of the soil (Singh and Benbi, 2016, 2018b; Sharma et al, 2019a) and crop productivity (Yang et al, 2012; Thind et al, 2019). Maintaining TOC stocks is important for sustainable agricultural development and the mitigation of global warming by reducing C emissions (Lal, 2004; Li et al, 2005; Singh and Benbi, 2020a)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
