Effects of different legume green manures on tropical soil microbiology after corn harvest

Abstract

Legume green manure is a popular practice for sustainable agriculture in tropical environments. The use of grain, forage and purely green manure legumes in a subhumid tropical area in Northeast Brazil was investigated to determine the total C and N contents and estimate C-microbial biomass, soil basal respiration, microbial and metabolic quotients, before and after green manures and after the following corn. It was hypothesized that, although all legumes would increase microbial biomass and activity, there would be different effects in function of the main economic usage of the legume. The experimental design evaluated the soil before and after harvest of seven legumes: (i) purely green manures -sunn hemp (Crotalaria juncea L.) and velvet bean (Stizolobium aterrimum Piper & Tracy); (ii) forage -Campo Grande stylo (a physical mixture of 80% of Stylosanthes captata Vog. and 20% of Stylosanthes macrocephala) and calopo (Calopogonium mucunoides Dev.) and (iii) grain -common bean (Phaseolus vulgaris L.), cowpea (Vigna unguiculata L.) and peanut (Arachis hypogaea L.), followed by corn crop. After corn harvest, soils had the same total C and N contents before legume seeding, but C-microbial biomass was significantly higher in soils with grain and purely green manures, which produced higher shoot and root dry mass. Soil basal respiration decreased after corn harvest for all legumes comparing to control treatments, but metabolic stress increased in soils with forage species. Despite this, microbial quotient indicated an efficiency of the microorganisms in degrading the residual organic matter of all green manures used in corn.

Biomassa e atividade microbiana do solo em pastagem degradada de Brachiaria decumbens após implantação de leguminosas herbácea

“…Comparing the C-mic obtained in the present study with those obtained by Barros et al (2020) for legume green manure soils with the implementation of peanut, stylosanthes, and calopo after corn harvesting, we conclude that these same herbaceous used here had an increase of ~50, 30 and 25 kg ha -1 , respectively, in the rainy season, two years after the start of cultivation, revealing the effectiveness of these legumes in stimulating the soil microbial community the soil. On the other hand, our highest C-mic results are similar to that reported by Lira-Junior et al (2020a) in the dry season, and the legume row found silvopastoral system based on shrub-tree legume Gliricidia sepium and Mimosa caesalpinifolia, but ca.…”

“…Forage production from Arachis pintoi, Stylosanthes sp., and Calopogonium mucunoides has been reported (Boddey et al, 2020;Kumar et al, 2018) as their effects on structural soil protection and nutrient input equalizing from decomposing microbial activity (Vazquez et al, 2020). In addition, the use of herbaceous has been well established in studies with legume green manure (Barros et al, 2020).…”

Meio Ambiente, Sustentabilidade e Tecnologia – Volume 7

“…In one evaluation of seven legumes green manure were able to maintain the total C and N contents in the soil after corn harvest. While forage legumes had higher metabolic stress than either grain or green manure ones, all the green manures presented lower stresses than either control treatment, indicating increased efficiency in organic matter decomposition (Barros et al, 2020).…”

Macronutrient availability and microbial population in fly ash amended alluvial soil

“…Among the different manures used, GLM performed well in improving the microbial population (Zhou et al, 2020). Because during the decomposition of fresh GLM, the activity of the microbes enhanced which in turn increased the microbial population (Barros et al, 2020). FYM also registered a significant result in the microbial population.…”