Abstract
Agricultural practices, specifically crop and land management schemes, greatly influence the ability of soil to produce CO2 under varying conditions. A 2-year research study was planned to quantify carbon-dioxide (CO2) emission fluxes and total C (TC) contribution in a no-till tropical soil under carambola with sunn hemp-velvet bean cover cropping (CC) systems. Composted poultry manure (PM) was applied as an additional N source. The treatments were fallow control (F), fallow with PM (FM), sunn hemp (SH), SH with PM (SHM), velvet bean (VB), and VB with PM (VBM). Average daily CO2 emission from VB was 23 and 15% higher than control and SH plots, respectively, during CC growing season. Similarly, CO2 emission after CC termination was highest from VB plots. About 17% higher CO2-C emission was observed from manure applied plots which indicates that additional food sources stimulated microbial activity in the soils and subsequently produced more CO2. However, total C contribution in SH plots were significantly higher than in VB plots and was more apparent when manure was not applied. Soil and air temperature played key roles in CO2 emission, specifically during the CC growing season. Considering both input and output parameters of C in the soil, our results suggest that SH has the better potential in reducing CO2 emission and accumulating more C in the soil than VB in tropical fruit orchard.
Highlights
Soil respiration plays a major role in global carbon (C) cycle (Schlesinger and Andrews, 2000; Gougoulias et al, 2014) and is actively related to soil ecosystem productivity
Termination, we observed that velvet bean (VB) with manure (VBM) plots produced the highest amount of CO2-C followed by SH with PM (SHM) (Figure 3)
41% of the total CO2 emission was found within 20 days after crop termination (DAT)
Summary
Soil respiration plays a major role in global carbon (C) cycle (Schlesinger and Andrews, 2000; Gougoulias et al, 2014) and is actively related to soil ecosystem productivity. Studies identify conservation or sustainable agriculture as an effective option for enhancing C storage, and in some cases, minimizing CO2 loss from agricultural soil (Martínez-Mena et al, 2021; Jia et al, 2021). Conservation or sustainable agriculture is the culmination of strategies for cultivating crops with minimal inputs, soil disturbances, and implementation of continuous soil cover (mulch) (Hobbs et al, 2008; Zhang and Peng, 2021). Cover cropping is recognized as one of the sustainable agricultural practices that influences soil C balance depending on soil types, land management, and environmental conditions. Ecosystem services provided from cover cropping include organic matter addition, soil structure improvement, weed control, nutrient management, and pollinator attraction, which are especially important in organic, low input systems (Scholberg et al, 2010).
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