Soil organic matter in crop rotations under no-till

Abstract

Soil organic matter conservation, paramount in tropical agriculture, is affected by the composition of cultivated plant species and the input of dry matter and nitrogen into the system. However, SOM development in tropical soils managed under no-till in the long term is not well understood. The objective of this study was to evaluate SOM concentration and quality as a result of crop rotations under NT in two soils in Botucatu, Brazil, over a 10-year experimental period (2003-2012). Crop rotations including grasses and a legume grown in the fall/winter and spring were conducted for seven years in a clay Rhodic Hapludox. In a clay Typic Rhodudalf, crop rotations were compared with a fallow/chiseled treatment for 10 years. The cash crop was soybean grown every year in the summer. In both experiments, SOM lability was affected mainly by the spring crops. The absence of spring cover crops in chiseled treatments resulted in less total organic carbon in the 0.0-0.10 m soil depth. Soil concentration of TOC and its fractions were higher under crop rotations with higher nitrogen input, especially where sunn hemp was grown in spring. The strongest effects occurred in the Typic Rhodudalf, probably as a result of its higher clay content and the longer period under crop rotation. Under NT, the increase in labile and stable SOM is limited by the lack of cover crops in the spring or N availability. However, SOM humification degree is decreased with higher C input. These results highlight the importance of the use of cover crops and nitrogen inputs in soil conservation strategies and the sustainability of agricultural systems in the tropics. 2015 Elsevier B.V. All rights reserved.

Vegetable yields and soil biochemical properties as influenced by fertilization in Southern China

“…A high C/N ratio results in the immobilization of N in the soil because of a relative excess of organic C, while a low C/N ratio results in the mineralization of N in the soil because of N excess (Raphael et al, 2016). In line with this, our results showed that the addition of organic manure reduced the C/N ratio compared to the NPK treatment, which indicated a larger N mineralization rate in the soil after manure application (Fig.…”

Soil compaction management and soybean yields with cover crops under no-till and occasional chiseling

“…Hubbard et al (2013) related that when sunn hemp was included in the rotation as a late summer cover crop, it added significantly more C to the soil than cropping systems with fallow in this period, improving soil physical proprieties. According to Raphael et al (2016), the soil concentration of SOM and its fractions were higher under crop rotations with higher nitrogen input, especially where sunn hemp was grown in spring, in an experiment carried out in the same experimental area and with the same treatments of the present experiment. Occasional chiseling was effective in maintaining high soybean yields for some time, but after 9 or 10 years yields observed in rotation with cover crops, and without chiseling were higher.…”

“…Calonego and Rosolem (2010) reported that cover crops left biopores in the soil profile, enhancing water infiltration and soybean root growth in depth. Besides, after 10 years, crop rotations resulted in better soil compared with chiseling (Raphael et al, 2016), because there was more soil organic matter accumulated up to 10 cm deep in the soil.…”

Traditional agriculture: a climate-smart approach for sustainable food production

“…The selection of a crop for incorporating it in rotations is very important. In crop rotation practice, species that enhance N in the soil can increase the phytomass production of the subsequent crops and consequently increasing SOM (Peoples and Baldock 2001;Raphael et al 2016). Increasing SOM is a sustainable method to enhance crop productivity while increasing carbon sequestration and maintaining global C-cycle.…”