Soil aggregation according to the dynamics of carbon and nitrogen in soil under different cropping systems

Abstract

-The objective of this work was to evaluate total soil carbon and nitrogen, as well as their contents in particulate and mineral-associated C fractions; to determine C stock and sequestration rates in the soil; and to verify the effect of C and N contents on soil aggregation, using different crop rotations and crop sequences under no-tillage. The study was carried out for nine years in a clayey Oxisol. The treatments consisted of different cropping systems formed by the combination of three summer crops (cropped until March) -corn (Zea mays) monocropping, soybean (Glycine max) monocropping, and soybean/corn rotation -and seven second crops (crop successions). Soil samples were taken at the 0.00-0.10-m layer for physical fractionation of C and N, and to determine soil aggregation by the wet method. Soybean monocropping increased C and N in particulate C fraction, while the crop systems with corn monocropping x pigeon pea (Cajanus cajan), corn monocropping x sun hemp (Crotalaria juncea), and soybean monocropping x corn as a crop succession increased total C in the soil. Greater rates of soil C sequestration were observed with soybean/corn rotation and with soybean monocropping, as well as with sun hemp as a second crop. The increase in total N increases soil C stock. Soil aggregation was most affected at particulate C fraction. Increases in soil N promote C addition to particulate fraction and enhance soil aggregation.

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

“…While superficial soil total C and N contents found after legume or corn harvest exceeded those found by Seben Junior et al (2016) in no-tillage corn intercropped with legumes and Muchane et al (2020) in subhumid soils under an agroforestry system, they are similar to those described by Lira Junior et al (2020) after two years of a subhumid tropical legume-shrub-tree based silvopastoral system. This reinforces these legumes potential to contribute to the storage of C and N in these soils over time, without the need for nitrogen inputs, as also reported by Ambrosano et al (2009) for corn growing systems with velvet bean and sunn hemp, both traditional tropical green manures.…”

Whether Wheat–Maize Rotation Influenced Soil Organic Carbon Content in Sushui River Basin

“…Therefore, the first hypothesis, that wheat-maize rotation did not significantly increase SOC content, was rejected. This finding is similar to the results reported by Seben Junior et al [24], where the effect of crop rotation was lower than that of soybean monoculture and higher than that of maize monoculture in soybean-maize rotation versus monoculture.…”

“…However, a study showed that the SOC content is higher in rice monocrops than in rice-wheat rotations [3]. Similar results have been observed under soybean cultivation, with SOC content being higher under monocropping than under soybean-maize rotation, and that under soybean monocropping, the SOC content was significantly higher than that under maize monocropping [24]. Did wheat-maize rotation and straw returning significantly affect soil organic carbon in the Sushui River Basin?…”

Silage yield, organic carbon content and physical attributes of a chiseled Ferralsol under an integrated crop-livestock system

“…The benefit of chiseling in increasing TOC content in relation to no-tillage is attributed to incorporating plant material into the soil every other year, four times in nine years of study. This plant material is generally coarser than plant material incorporated in the conventional tillage, which favors the slow and gradual decomposition of the residue incorporated by the chiseling (Olson et al, 2016;Seben Junior et al, 2016). Chiseling does not fully expose the compost/residue to microorganism action and oxygen which accelerates the degradation process, and which usually occurs in conventional tillage, favoring the results observed in this treatment in the 0.00-0.05 m layer.…”

“…It is known that grasses have a primordial effect on soil structuring due to improved aggregation (Seben Júnior et al, 2016). However, diversified cover crops must be adopted to improve the soil physical quality; in this context legume insertion could improve the structural quality of the soil under no-tillage because their root system favors forming macropores (Seben Junior et al, 2016;Calonego et al, 2017;Reichert et al, 2017). Crop diversification is necessary for chiseling to be an effective management of the area.…”