Effectiveness of crop straws and swine manure in ameliorating acidic red soils

Authors: CAI, ZEJIANG - Chinese Academy Of Agricultural Sciences; XU, MINGGANG - Chinese Academy Of Agricultural Sciences; WANG, BOREN - Chinese Academy Of Agricultural Sciences; ZHANG, LU - Chinese Academy Of Agricultural Sciences; WEN, SHILIN - Chinese Academy Of Agricultural Sciences; Gao, Suduan

Submitted to: Journal of Soils and Sediments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2018
Publication Date: 3/25/2018
Citation: Cai, Z., Xu, M., Wang, B., Zhang, L., Wen, S., Gao, S. 2018. Effectiveness of crop straws and swine manure in ameliorating acidic red soils. Journal of Soils and Sediments. https://doi.org/10.1007/s11368-018-1974-7.
DOI: https://doi.org/10.1007/s11368-018-1974-7

Interpretive Summary: Intensive use of chemical fertilizers has caused accelerated soil acidification, severe soil degradation, and crop yield reduction in subtropical regions with red soils in Southern China. Soil amendment with organic materials has the potential to mitigate soil acidification because of their ash content. This research determined amendment effects of soybean straw, maize straws, and swine manure on soil acidity, base cations, and nitrogen dynamics. All three materials raised soil pH significantly as amendment rate increased. Soybean straw resulted in highest soil pH in a less acidic soil or more effectively than the manure. However, swine manure reduced the toxic levels of exchangeable aluminum most effectively. This research suggests that both manure and crop residual return to soil could be long-term management strategies for acidic soils.

Technical Abstract: Purpose: Crop straws and animal manure have the potential to ameliorate acidic soils, but their effectiveness and mechanisms are not fully understood. The aim of this study was to examine crop (maize, and soybean) straws, swine manure, and their application rates on acidity changes in acidic red soil (Ferralic Cambisol). Materials and methods: Two soils were collected from Red Soil Experimental Station of the Chinese Academy of Agricultural Sciences at Qiyang, Hunan Province with 1) no fertilization history (CK soil, pH 5.46) and 2) received 21-years of chemical nitrogen (N) fertilization (N soil, pH 4.18). After incorporation of the straws or manure at 0, 5, 10, 20, and 40 g kg-1 (w/w), the soils were incubated and examined for changes in pH, exchangeable acidity, N mineralization, and speciation as ammonium (NH4+) and nitrate plus nitrite (NO3-+ NO2-) for 105 days. Results and discussion: All three organic materials decreased significantly soil acidity (dominated by aluminum) as the application rate increased. At 40 g kg-1 treatment, soybean straw increased the CK soil pH the highest (more effective than manure) and all three organic materials showed similar effect on pH increase in the N soil. Swine manure was more effective than the straws to reduce exchangeable aluminum in the highly acidic N soil from initial 5.79 cmol(+) kg-1 to 0.50, compared to 2.82 and 4.19 cmol(+) kg-1 by soybean straw and maize straw, respectively while all three materials reduced soil exchangeable acidity and increased soil base cations similarly in the less acidic CK soil. The NO3-+NO2- concentration in soil increased significantly from swine manure, but decreased markedly for straws treatments. The high C/N ratio in the straws led to N immobilization and pH increase. Conclusions: This research concludes that while swine manure continues to be an effective nutrient and waste management tool that can effectively ameliorate soil acidity, crop straw amendments also showed the potential to ameliorate acidity of the red soil. The long-term effect of straw return on soil acidity management warrants further investigation under field conditions.