Effect of Large-Scale Cultivated Land Expansion on the Balance of Soil Carbon and Nitrogen in the Tarim Basin

Abstract

Land reclamation influences the soil carbon and nitrogen cycling, but its scale and time effects on the balance of soil carbon and nitrogen are still uncertain. Taking the Tarim Basin as the study area, the impact of land reclamation on the soil organic carbon (SOC), total nitrogen (TN), and carbon to nitrogen (C:N) ratio was explored by the multiple temporal changes of land use and soil samples. Remote sensing detected that cropland nearly doubled in area from 1978 to 2015. Spatial analysis techniques were used to identify land changes, including the prior land uses and cultivation ages. Using land reclamation history information, a specially designed soil sampling was conducted in 2015 and compared to soil properties in ca. 1978. Results found a decoupling characteristic between the C:N ratio and SOC or TN, indicating that changes in SOC and TN do not correspond directly to changes in the C:N ratio. The land reclamation history coupled with the baseline effect has opposite impacts on the temporal rates of change in SOC, TN and C:N ratios. SOC and TN decreased during the initial stage of conversion to cropland and subsequently recovered with increasing cultivation time. By contrast, the C:N ratio for soils derived from grassland increased at the initial stage but the increase declined when cultivated longer, and the C:N ratio decreased for soils derived from forest and fluctuated with the cultivation time. Lower C:N ratios than the global average and its decreasing trend with increasing reclamation age were found in newly reclaimed croplands from grasslands. Sustainable agricultural management practices are suggested to enhance the accumulation of soil carbon and nitrogen, as well as to increase the C:N ratio to match the nitrogen deposition to a larger carbon sequestration.

Impact of agricultural abandonment on soil organic carbon: The case of semi‐steppe rangeland in Central Iran

“…As shown by Kashi et al (2016), soil erosion by water and/or tillage has a significant impact on the SOC. These findings are also consistent with the findings of Xu et al (2019) and Yao et al (2019).…”

“…F I G U R E 6 PC1 (57.6% of the variation) and PC2 biplot (24.3% of the variation) dividing three land uses including cultivated rangelands (CR0), rangelands abandoned for 15 years (AR15), and rangelands abandoned for 40 years (AR40). Min-C, mineralization carbon; MWD, mean weight diameter; N, soil total nitrogen; SOC, soil organic carbon; UR, uncultivated rangelands [Colour figure can be viewed at wileyonlinelibrary.com] These findings are also consistent with the findings of Xu et al (2019) and Yao et al (2019).…”

Changes in Soil Organic Carbon Under Continuous Farming

“…Subsequent to late fertilisation, this area has indicated a comparable total N when compared with 2014. Such findings are similar to Xu et al (2019) and Kushwah et al (2014) which have obtained a lower C/N ratio in the initial stages of crop development, however these will be elevated slowly afterward. However, it has indicated a decline of C/N ratio when the converted crop cultivation area, for example, forest to cultivation trend from forest > grassland > cropland (Xu et al, 2019).…”

“…The cultivation of a land for agricultural activities has a major impact on soil organic carbon (OC). Literally, a forest system will retain the most source of C followed by grassland, whereby the lowest may be found in cropland (Xu et al, 2019;Evrendilek et al, 2004). According to Evrendilek et al (2004), a decrease of OC content of up to 43% occurred when grassland was converted into cropland on a 12 year period, led by land disturbance of particular area that had facilitated organic matter (OM) decomposition.…”

Effects of Chicken Compost and KCl Fertilizer on Growth, Yield, Post-Harvest Quality of Sweet Corn and Soil Health

“…This is because the energy source for soil microbes has been exhausted, so microbial activity also declines. During the decomposition process, there will be a reduction in the C/N ratio of organic matter, and this is based on the decomposition process, causing the C/N ratio to become lower such that organic material decomposition continues during the plant growth process (Xu, Zhang, & Xu, 2019). Sharma & Banik (2014) have posited that C-organic is the basic energy source of soil microbes.…”