Redistribution and loss of soil organic carbon by overland flow under various soil management practices on the Chinese Loess Plateau

Abstract

Field rainfall simulations with intensities of 85 and 170 mm/h were conducted in 2002 and 2005 on a 15-m long slope on a loess soil in Luoyang, Henan Province, P. R. China to study the effects of different soil management practices on the redistribution and loss of soil organic carbon (SOC) by runoff and soil erosion. Field plots under winter wheat ( Triticum aestivum L.) were set up in 2001 and included the following soil management practices: subsoiling with mulch (SSM), no-till with mulch (NTM), reduced tillage (RT) and conventional tillage control (CT). The results showed that SOC for topsoil (0 - 20 cm) increased in the NTM and SSM plots when compared with results from 2002 and 2005. For all treatments, SOC in the lower part of the plots was higher in 2005 than in 2002. The values from the upper parts of the plots were only lower in 2005 compared with the overall values for 2002 for RT and CT. The enrichment ratio of organic carbon (ERoc) in runoff sediment varied from 1.01 to 2.24 with a mean of 1.25. During the simulated rainfall events, ERoc was initially high and then reduced after a short period to reach a steady value at the end of the event, always remaining >= 1. The change in SOC loss rate was more dependent on the sediment loss rate than on the changes in SOC concentration in the sediment. The best results in terms of a reduction in soil and SOC loss were obtained with NTM: no runoff and hence no soil and SOC loss were observed. SOC losses observed for SSM were on average only 4% of those observed for CT. RT resulted in 71% SOC loss compared with CT although the runoff reduction was not pronounced. For farmers, SSM and NTM are the best alternatives in terms of SOC conservation. NTM has the additional advantage that it requires less labour and is more beneficial from economic and environmental perspectives

Soil crusting impact on soil organic carbon losses by water erosion

“…Moreover, as suggested by the work of Tisdall and Oades (1982) on aggregate stability, the clayey texture at ERO is likely to generate relatively stable aggregates with a high organic matter content and these aggregates are more likely to be detached and transported. This is partly confirmed by our own results, where ER was significantly correlated with soil clay content, which was in concordance with the findings of Avnimelech and McHenry (1984) and Jin et al (2009). Finally, ER increases with sand content in soil, which is in accordance with the finding of Feller et al (1991) who suggested that organic carbon content in soil decreases with increasing sand proportion in the soil.…”

“…The average enrichment of sediments in organic carbon was found in STRU crust to be 1.23, which was consistent with previous findings (Bertol et al, 2007;Girmay et al, 2009;Mchunu and Chaplot, 2012;Morsli et al, 2006;Moyo, 1998). This was previously explained by the light nature of organic matter that makes it easily transported by runoff (Avnimelech and McHenry, 1984;Jin et al, 2009). The low enrichment ratio of sediments from DES, GRAV and ERO crusts could be explained by the physical protection that surface crust confer to the soil layer underneath, as suggested by Fig.…”

Heavy metal accumulation in soils and grains, and health risks associated with use of treated municipal wastewater in subsurface drip irrigation

“…Adding wheat straw during crop maturity of wheat slightly increased SOC compared to corn (p<0.05). Long-term planting of crops with residue remaining on the field after harvesting could gradually increase the amount of SOC in soils that have low amounts of it (Jin et al 2008).…”

Traditional Tillage Systems as Drought Adaptation Strategies of Smallholder Farmers: The Case of Semi-Arid Central Tanzania

“…In general, smallholder farmers perceived farms that are exposed to no-till to have low soil fertility. Contrary to their perceptions, fieldbased research that assessed influence of continuous application of no-till, ridging, and other tillage practices in different areas revealed no-till to contain more soil organic carbon (Jin et al 2008;Yoo and Wander 2006) and high total nitrogen (Malhi et al 2006;Papini et al 2006). Furthermore, field experiments on assessing the influence of different tillage practices on exchangeable cations have revealed notill treatments to be rich in calcium, potassium, magnesium and sodium compared to other practices (Hussain et al 1999).…”