Conservation Tillage and Fertilization Impact on Soil Aggregation and Carbon Pools in the Indian Himalayas Under an Irrigated Rice-Wheat Rotation

Abstract

Soil conservation and carbon sequestration are critical issues in the Indian Himalayas. This study, conducted from 2005 through 2009 on a sandy clay loam soil near Almora, India, with two tillage (conventional tillage [CT] and zero tillage [ZT]) and five fertilization management practices (100% NPK [F1], 50% NPK + 10 Mg farmyard manure [FYM] ha j1 [F2], 50% NPK + 10 Mg poultry manure [PM] ha j1 applied on equivalent N basis of 10 Mg FYM ha j1 [F3], 100% NPK + 10 Mg FYM ha j1 [F4], and 100% NPK + 10 Mg PM ha j1 applied on equivalent N basis of 10 Mg FYM ha j1 [F5]). The effects of these practices on soil organic carbon (SOC) retention and its physical and chemical pools, soil aggregation, and aggregate-associated C contents in the 0-to 15-cm soil layer were evaluated. The plots under ZT had nearly 11% and 12% higher total SOC and particulate organic matterYC (POM-C) concentrations, respectively, compared with CT (È12 and 4 g kg j1 soil, in that order) plots in the 0-to 5-cm soil layer. Plots under F4 and F5 had significantly higher total SOC and POM-C contents than F2-and F3-treated plots in both soil layers. Although the labile pools of SOC were positively affected by ZT and fertilization, the recalcitrant pool was not. Plots under ZT had higher macroaggregates, mean weight diameter (MWD), and macroaggregate-associated SOC compared with CT in the surface soil layer only. Similarly, F4-or F5-treated plots had higher macroaggregates, MWD, and macroaggregate-associated SOC compared with F1-, F2-, or F3-treated plots in that layer. All C pools had significant positive relationship with the MWD (in millimeters) in the 0-to 5-cm soil layer (n = 40), except for the nonlabile pool. However, only very labile (Pool I) and labile (Pool II) C pools had significant relationships with the proportion of macroaggregates in the 0-to 5-cm soil layer. Thus, adoption of year-round ZT along with 100% NPK in rice and 100% NPK + FYM/PM addition in wheat is the best management option under an irrigated rice-wheat system in the Indian Himalayas, as the management practice has the potential to maintain productivity and improve soil aggregation with greater accumulation of POM-C and SOC stabilization.

Integrative effects of no-tillage and straw returning on soil organic carbón and water stable aggregation under rice-rape rotation

“…The interaction among soil aggregate size distribution, SOC contents and aggregate stability indices is still not well understood (Blanco-Canqui and Lal, 2004). Meanwhile, little information is available about whether soil aggregate stability is positively or negatively correlated with soil C (Six et al, 2002;Bhattacharyya et al, 2012). Based on recent literature, it is perceived that less studies have investigated the interactive effects of tillage and straw returning in rice-rape rotation system regarding SOC and water stable aggregation.…”

“…The soil management practices are considered essential to conserve soil quality (Kahlon et al, 2013), and can greatly affect the composition and stability of SOC through plough layer (Stone and Schlegel, 2010;Bhattacharyya et al, 2012;Ghosh et al, 2016). Conventional tillage (CT) could reduce the SOC content and accelerate SOC oxidation rate, probably due to the disturbance of soil aggregates and the increase of the soil aeration (Gathala et al, 2015).…”

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

“…Pandey et al, (2014) revealed that no-tillage before sowing of rice and wheat could increase SOC by 0.59 Mg C ha -1 yr -1 . The rate of SOC sequestration due to reduced-or no-tillage management in rice-based systems in South Asia varied from 0-to 2114 kg ha -1 yr -1 (Bhattacharyya et al, 2012a).…”

Effects of Resource Conservation Practices on Productivity, Profitability and Energy Budgeting in Maize–Wheat Cropping System of Indian Sub-Himalayas

“…The VS reduces runoff and soil loss by deposition of sediments carried by runoff water behind the strips to form vegetative bund over the years [20,24], whereas weed mulch reduces rainfall's erosion potential by preventing breaking down of large water stable aggregates that reduces soil erosion [24]. Reduction of runoff and soil through bio-resources (FYM, VC and PM) recycling is expected as carbon input from organic sources helps in formation of more water stable macro-aggregates [6]. As independent components of CA reduce runoff and soil loss, therefore, interaction effect of the components obviously reduces runoff and soil loss by higher quantity.…”

“…When vegetation strips integrate with reduced tillage, nutrient management (bio-resources like FYM, vermi-compost and poultry manure) and weed management, it can lead to a sustainable production system in Indian sub-Himalayas where *82 % of the population lives in rural areas and is chiefly dependent upon crop farming [5]. Minimum tillage is recommended for soils of the Indian Himalayan region due to reduced cost of cultivation, more retention of soil water and physical protection of soil organic carbon (SOC) in the aggregates [6]. Bio-resource in situ (weed live mulch) and ex situ (FYM, vermi-compost, poultry manure) recycling not only fulfils nutrient requirement of a crop cycle but also increases soil water storage.…”