Maintenance Of Organic Carbon Research Articles

Alteração das frações da matéria orgânica em solo cultivado com cana-de açúcar na transição Cerrado-Amazônia

ABSTRACT The use of agroindustrial wastes, such as vinasse, may alter the soil chemical and physical characteristics. This study aimed to evaluate the total organic carbon and total nitrogen in a soil and the distribution of carbon and nitrogen in the sand and clay granulometric fractions, in three management systems (with and without vinasse application and with burning for harvest, in comparison with primary/native forest coverage), regarding fertilization and harvesting of sugarcane, in the Midwest region of Brazil. The use of organic wastes in the sugarcane production system may promote, even in a short time frame, conservation and improvement of the soil quality by the addition and maintenance of organic carbon. The use of vinasse favors the increase of the total organic carbon and total nitrogen in the soil, in the clay fraction, at all evaluated depths. The system with burning results in lower total carbon levels in the sand fraction, in comparison with the clay fraction, and, even with the sugarcane harvest employing burning, the most recalcitrant organic matter is associated with the clay fraction.

Rice–wheat cropping system: tillage, mulch, and nitrogen effects on soil carbon sequestration and crop productivity

Maintenance of organic carbon in soil (SOC) is critically important for sustained agricultural productivity and environmental quality. This paper presents SOC resulting from differences in tillage types and demonstrates how mulch and nitrogen (N) application can mediate the tillage functions on SOC and crop productivities. The results are derived from a 4-year field-scale study carried out in a low-land under sub-tropical hot and humid environment of Nepal. It compared eight treatment combinations, viz., tillage (no-tillage and conventional tillage), mulch (no-mulch and 12 Mg ha−1 year−1 of mulch), and N application (recommended versus leaf color chart method) under rice–wheat cropping system. Seasonal grain and biomass yields of these crops were recorded and at the end of the 4-year study, quantified the organic carbon stock of soil; Within 15 cm of surface soil, SOC stock (Mg C ha−1) was statistically (p < 0.05) higher on no-tillage plots (11.2–11.8) than on conventional tillage plots (9.2–10.5). The treatment effect was more pronounced on winter wheat productivity where conventional tillage combined with straw-mulch exceled the performance of no-tillage. Clearly, no-tillage had the environmental benefit, and conventional tillage had the crop productivity benefit.