Decomposition and Nutrient Release Dynamics of Shoot Phytomass of Cover Crops in the Recôncavo Baiano

Abstract

ABSTRACT:Evaluating the decomposition dynamics of vegetative residues from cover crops can provide a better understanding of nutrient release, which is fundamental when choosing a species that is adapted to local conditions. The objective of this study was to evaluate the decomposition rates and nutrient release dynamics of the shoot phytomass of different cover crops that have potential for agricultural use in the Recôncavo Baiano, Brazil. Crop residues of the following species were analyzed: sunn hemp (Crotalaria juncea L.) -CROT; velvet bean (Mucuna aterrima L.) -MUC; lab lab (Dolichos lab lab L.) -LAB; jack bean (Canavalia ensiformis [L.] DC.) -JB; white lupin (Lupinus albus L.) -WLUP; and Guinea grass (Urochloa maxima (Jacq.) R. Webster) -GRAS. The experiment was conducted in a randomized block design with four replications. The decomposition and nutrient release dynamics were evaluated using litter bags, and the remaining dry matter and the nutrient content of litter from each cover crop were quantified. The accumulation of macronutrients in the phytomass was in the following order: N > K > Ca > Mg > P > S. The highest decomposition rates of the phytomass occurred in the species JB, with half-life (t 1/2 ) of 36 days, and GRAS, with t 1/2 of 41 days. K was the element with the shortest t 1/2 , suggesting a rapid transfer rate to the soil. Organic residues from the CROT and WLUP cover crops had lower decomposition rates and are, therefore, recommended for protecting soil in the region. Sunn hemp, unlike WLUP, also had residue of high chemical quality and, thus, it is an excellent nutrient recycler. Jack bean released nutrients into the soil the fastest due to its rapid decomposition rate; therefore, it is not recommended for ground cover.

Do cover crops improve the productivity and industrial quality of upland rice?

“…The shortest Ca half-life was observed for sunn hemp (52 d), pigeonpea (68 d), and millet + sunn hemp (63 d) straw, and the longest in the straw of the fallow treatment (107 d). The Ca half-life results were similar to those obtained for the DMCCs half-life, demonstrating that Ca release is dependent on the decomposition of cover crops residues, because Ca is a constituent of the middle lamella of the cell wall (Taiz et al, 2017), one of the most recalcitrant plant tissue components (Xavier et al, 2017).…”

Effects of trees and nitrogen supply on macronutrient cycling in integrated crop–livestock systems

“…Potassium was the nutrient with the lowest concentration in litter bags at the end (120 d) of the incubation period, that is, on average, 3.0 (Figure 2) and 11% (Figure 3) for pasture and soybean residues, respectively. Rapid releases of K had been reported by others (Assmann et al., 2014; Xavier, Oliveira, & Silva, 2017). These results were attributed to K not being found in plant structural components (Hawkesford et al., 2012).…”

Nutrient cycling in multifunctional agroecosystems with the use of plant cocktail as cover crop and green manure in the semi-arid

“…However, understanding the residue decomposition dynamic and nutrients immobilization/mineralization in the soil is necessary to identify the most adapted species combination (Xavier et al, 2017). Those species must have characteristics related to climate adaptation and tolerance to drought, biomass production and soil cover efficiency, biological fixation of nitrogen (BFN), decomposition rate and cycling and accumulation of nutrients (Roberts and Mattoo, 2018).…”

“…The evaluation of plant residues decomposition added to the soil by cover crops provides a better understanding of nutrient supply for important commercial crops (Xavier et al, 2017). Typically, species are grouped into two decomposition classes using C/N rate value to separate them in those with rapid decomposition and with slow decomposition rate, which is accepted a C/N value close to 25 as references to separate these groups (Wider and Lang, 1982).…”