Residue decomposition dynamics in mixed ratios of two warm‐season cover crops

Abstract

Cover crop residue management has gained attention over the past few decades due to the potential of cover crop residues to provide soil cover and nutrient availability for subsequent crops. Nutrients released from cover crop residues depend on the nutrient composition of plant tissue and ensuing rates of mineralization. To evaluate the rate of carbon (C) and nitrogen (N) mineralization from cover crops, a field decomposition experiment was conducted in a humid subtropical agricultural field. Residues of two warm-season cover crops, sunn hemp (Crotalaria juncea L.) and sorghum sudangrass (Sorghum bicolor L. × S. bicolor var. Sudanese), were placed in litterbags at various mixture ratios on the soil surface to quantify the amount of N and C released from the residues over 56 d. Residue biomass decomposition followed decay patterns that were similar despite treatment mixtures of cover crop ratios. The initial ratio of cover crop material in the litter mixture influenced early N release where ratios with increasing sunn hemp increased N decomposition. The majority of residue breakdown (50-75%), and C (50-75%) and N (65-75%) decomposition occurred during the first 7 d for all the treatments. A minor fraction of residue remained (10-14%) at Day 56, with 10-14% C and 7-25% N. The 25% N remained in the sole sorghum sudangrass treatment. These results indicate that N from legume cover crops may not be available to subsequent crops in humid subtropical soils lacking the capacity to retain nutrients leached out of cover crop residue, though small fractions of dry matter may remain.

Different leafy vegetable cropping systems regulate growth, photosynthesis, and PSII functioning in mono-cropped eggplant by altering chemical properties and upregulating the antioxidant system

“…Many studies have reported that in crop rotation, below-ground rhizodeposits and root addition are the key factors of carbon accumulation in the soil, accounting for up to 75% of soil organic matter (Jones et al, 2009;Ghani et al, 2022d). Different types of crop stalks, twigs, dead roots as well as fallen leaves are important sources of nutrients Aschi et al (2017), while leafy vegetables used as crop rotation can scavenge nutrients from the soil, store it in their residues and return it to the soil for the next crop through root decomposition and improved SOM (Dorissant et al, 2022;Ghani et al, 2022b). Kong and Six (2012) reported that living cover crops significantly improved soil organic matter compared to bare fallow due to the rhizodeposition of low molecular carbon into the soil.…”

Exploring the Impact of Tillage Methods on Crop Residue Decomposition and Nutrient Release: A Litter Bag Study

“…The ground samples were analysed for N (Bremner and Mulvaney 1982),C and P (Chapman and Pratt 1961). Residue from each bag was also prepared and burned to identify soil mineral contaminants in a furnace at 550C for 4 h. Litterbag content is reported on an ash-free dry weight basis (Dorissant et al 2022).…”