Cai Liqun

Effects of different conservation tillage measures on soil organic carbon pool in two sequence rotation systems of spring wheat and peas.

A 5-year conservation tillage experiment was conduced in Lijiabu, Dingxi City of Gansu Province to study the effects of crop rotation and tillage on soil total carbon, active organic carbon, microbial biomass carbon and soil organic carbon pool manage-ment index. The results show that conventional tillage with straw mulching and conventional tillage, in which straw is plowed into soil, increase soil organic carbon, active organic carbon, microbial biomass carbon and soil carbon pool management index under both rotation sequences. Though zero-tillage increases soil carbon pool management index in 0 ~5 cm soil layer, it decreases index of the other soil layers. The findings then suggest that zero-tillage without straw mulching or straw plowing into the soil is non-sustainable for soil organic carbon management.

Different carbon sources enhance system productivity and reduce greenhouse gas intensity

Yeboah S., Zhang R.Z., Cai L.Q., Jun W. (2018): Different carbon sources enhance system productivity and reduce greenhouse gas intensity. Plant Soil Environ., 64: 463–469. The aim of this study was to investigate the effect of biochar, straw and nitrogen (N) fertilizer on soil properties, crop yield and greenhouse gas intensity in rainfed spring wheat (Triticum aestivum L.), and to produce background dataset to improve nutrient management guidelines for semiarid environments. The two carbon sources (straw and biochar) were applied alone or combined with nitrogen fertilizer (urea, 46% N), whilst the soil without carbon amendment was fertilized by urea in the rates 0, 50 and 100 kg N/ha. The experiments were arranged in a randomized complete block design with three replicates. The greatest yields were found with 100 kg N/ha under biochar, straw and soils without carbon. Biochar treated soils produced the greatest grain yield at 1906 kg/ha, followed by straw at 1643 kg/ha, and soils without carbon at 1553 kg/ha. This was explained by increased easily oxidizable carbon and total soil nitrogen in the biochar treated soil (P < 0.05). Straw treated soils and soils without carbon increased global warming potential by 13% and 14% compared to biochar amended soils. The biochar amended treatment also improved easily oxidizable carbon and total nitrogen (P < 0.05), which supported the above results. BN100 (15 t/ha biochar + 100 kg N/ha) reduced greenhouse gas intensity by approximately 30% compared to CN100 (100 kg N/ha applied each year) and SN50 (4.5 t/ha straw applied each year + 50 kg N/ha). Based on these results, biochar could be used with N-fertilizer as a soil conditioner to improve yield and reduced greenhouse gas intensity.

Soil respiration and net ecosystem production under different tillage practices in semi-arid northwest China.

Lamptey S., Li L., Xie J., Zhang R., Luo Z., Cai L., Liu J. (2017): Soil respiration and net ecosystem production under different tillage practices in semi-arid Northwest China. Plant Soil Environ., 63: 14–21. In semi-arid areas, increasing CO2 emissions are threatening agricultural sustainability. It is unclear whether different tillage practices without residue returned could help alleviate these issues while increasing crop productivity. This study aimed to quantify soil respiration under conventional tillage (CT); rotary tillage (RT); subsoiling (SS) and no-till (NT), all without residue returned in the Western Loess Plateau. The results showed that SS and NT significantly decreased soil respiration compared to CT, but the effects of SS was the greatest. As a result, SS decreased carbon emission by 22% in 2014 and 19% in 2015 versus CT. The trends of net ecosystem production under different tillage systems were as follows: CT > RT > NT > SS. No-till increased net ecosystem production by 33% in 2014 and 12% in 2015 relative to CT. The SS treatment increased average grain yield by 27% and 23% over CT and RT, and enhanced water use efficiency by an average of 43%. On average, SS increased carbon emission efficiency by 60% and 43% compared to CT and RT, respectively. Thus, subsoiling management strategy is a promising option for the development of sustainable agriculture in semi-arid areas.