Tillage and Irrigation Effects on Soil Aggregation and Carbon Pools in the Indian Sub‐Himalayas

Abstract

Carbon retention is a critical issue in arable farming of the Indian Himalayas. Th is study, conducted from 2001 through 2010 on a sandy clay loam soil, evaluated the eff ect of tillage alterations (conventional tillage [CT] and zero tillage [ZT]) and selected irrigation treatments (I1: pre-sowing, I2: pre-sowing + active tillering or crown root initiation, I3: pre-sowing + active tillering or crown root initiation + panicle initiation or fl owering, and I4: pre-sowing + active tillering or crown root initiation + panicle initiation or fl owering + grain fi lling), applied at the critical growth stages to rice (Oryza sativa L.) and wheat (Triticum aestivum L.) on soil organic C (SOC) retention and its pools, soil aggregation, and aggregate-associated C contents in the 0-to 30-cm soil layer. Results indicate that the plots under ZT had nearly 17 and 14% higher total SOC and particulate organic C contents compared with CT (~9.8 and 3.6 g kg -1 soil) in the 0-to 5-cm soil layer aft er 9 yr of cropping, despite similar mean aboveground biomass yields of both crops on both CT and ZT plots. Tillage had no eff ect on C pools in the subsurface layers. Irrigation had positive impact on SOC content in the 0-to 5-and 5-to 15-cm layers. Although the labile pools of SOC were positively aff ected by ZT, the recalcitrant pool was not. Plots under ZT and I4 also had higher large and small macroaggregates and macroaggregate-associated SOC. Th us, adoption of ZT is the better management option for soil C improvement than CT, and irrigation generally enhances the positive impacts.

Effect of Organic Inputs on Strength and Stability of Soil Aggregates Associated Organic Carbon Concentration under Rice-Wheat Rotation in Indo-Gangetic Plain Zone of India

“…Bhattacharyya et al, 2013 found that small macro-aggregates accounted for >30% of the total aggregates (mean of both main plots) in the surface soil layer. Silt-plus clay-sized aggregates comprised the greatest proportion of the whole soil, followed by the small macro-aggregates.…”

Modelling soil water balance and root water uptake in cotton grown under different soil conservation practices in the Indo-Gangetic Plain

“…A higher Leaf Area Index (LAI) in the soil conservation practices than in the CT plots could be due to the compounded effects of many factors, such as an additional nutrient supply, decreased competition for resources due to a lower weed density, improved soil physical properties and water regimes, better radiation interception, water extraction, aeration and less evaporation in the soil conservation practices compared with the CT plots (Unger et al, 1998;Bhattacharya et al, 2012Bhattacharya et al, , 2013Das et al, 2014). Soil structure affects crop yield through a complex of root-based mechanisms, that in turn affect above-ground biomass (Passioura, 2002).…”

“…When the crop residues are retained on the soil surface, it initiates processes that lead to improved soil quality by protecting the soil from raindrops and limiting water evaporation. Therefore, CA may lead to sustainable improvements in the efficient use of water by increasing infiltration and soil water retention and reducing water losses due to evaporation, and by improving nutrient balances and their availability (Dahiya et al, 2007;Govaerts et al, 2007;Verhulst et al, 2010;Bhattacharya et al, 2013). CA also improves soil health (mainly by increasing SOM content).…”

Conservation agriculture effects on soil organic carbon accumulation and crop productivity under a rice–wheat cropping system in the western Indo-Gangetic Plains

“…Retention of green manures in rice helps to improve soil nutrient status and promotes soil microbial activity . These alternative practices are known to exert positive effects on chemical, physical and biological soil properties (Bhattacharyya et al, 2006(Bhattacharyya et al, , 2013a.…”