Changes in soil organic carbon and nitrogen after 26 years of farmland management on the Loess Plateau of China

Abstract

Soil carbon (C) and nitrogen (N) play a crucial role in determining the soil and environmental quality. In this study, we investigated the effects of 26 years (from 1984 to 2010) of farmland management on soil organic carbon (SOC) and soil N in abandoned, wheat (Triticum aestivum L.) non-fertilized, wheat fertilized (mineral fertilizer and organic manure) and alfalfa (Medicago Sativa L.) non-fertilized treatments in a semi-arid region of the Loess Plateau, China. Our results showed that SOC and soil total N contents in the 0-20 cm soil layer increased by 4.29 (24.4%) and 1.39 Mg/hm 2 (100%), respectively, after the conversion of farmland to alfalfa land. Compared to the wheat non-fertilized treatment, SOC and soil total N contents in the 0-20 cm soil layer increased by 4.64 (26.4%) and 1.18 Mg/hm 2 (85.5%), respectively, in the wheat fertilized treatment. In addition, we found that the extents of changes in SOC, soil total N and mineral N depended on soil depth were greater in the upper soil layer (0-30 cm) than in the deeper soil layer (30-100 cm) in the alfalfa land or fertilizer-applied wheat land. Fertilizer applied to winter wheat could increase the accumulation rates of SOC and soil total N. SOC concentration had a significant positive correlation with soil total N concentration. Therefore, this study suggested that farmland management, e.g. the conversion of farmland to alfalfa forage land and fertilizer application, could promote the sequestrations of C and N in soils in semi-arid regions.

Soil Gaseous Emissions and Partial C and N Balances of Small-Scale Farmer Fields in a River Oasis of Western Mongolia

“…Alfalfa cultivated in monoculture under dry climate conditions was reportedly able to sequester about 560 kg C ha −1 a −1 and about 25 kg N ha −1 a −1 in an oasis of Gansu province, northwest China [58]. Under semi-arid climate conditions, about 190 kg C ha −1 a −1 and 45 kg N ha −1 a −1 were accumulated in a long-term experiment in the Shaanxi province, China [59]. Even more N (up to 29%) could be fixed to soil by alfalfa if the legume is cultivated in combination with grasses [60].…”

Soil CO2 Uptake in Deserts and Its Implications to the Groundwater Environment

“…Since the potential contributions of these abiotic components to the total soil CO2 fluxes were non-negligible, the implication of the biotic CO2 effluxes and abiotic CO2 influxes to the soil-groundwater environment cycle is a subsequent problem. Despite the recent studies of soil carbon cycle in the desert ecosystems and the biogeochemical investigations in the arid ecosystems [40][41][42][43][44][45][46][47][48][49], the dynamics of beneath CO2 dissolution [7,10] is still not well-understood. Furthermore, even the mechanisms of subterranean abiotic processes are still not wholly known.…”

Recovery Role in Soil Structural, Carbon and Nitrogen Properties of the Conversion of Vegetable Land to Alfalfa Land in Northwest China

“…Many soil properties (e.g., soil structural properties, C, and N properties) that affect agricultural productivity and ecosystem function are influenced by the soil C and N status (Lal 2002). In addition, soil C is often associated with major nutrients, especially N, and hence influences the cycling and availability of nutrients for crop and pasture production (Zhou et al 2015). Appropriate land use and soil management can improve the soil quality (Zhou et al 2015;Khan et al 2019).…”

“…In addition, soil C is often associated with major nutrients, especially N, and hence influences the cycling and availability of nutrients for crop and pasture production (Zhou et al 2015). Appropriate land use and soil management can improve the soil quality (Zhou et al 2015;Khan et al 2019). It not only improves land productivity, but also regulates the balance of soil C and N, and improves surface soil structural properties (Lal 2002;Su 2007).…”