Effects of Conservation Tillage on Soil Physicochemical Properties and Crop Yield in an Arid Loess Plateau, China.

Conservation tillage can improve soil physical structure and water storage, protect moisture, and increase crop yield. However, the long-term adoption of a single tillage method may have some adverse effects on soil and ecological environment, although crop yields have increased. Through informed allocation of soil tillage techniques, the combination and configuration of soil tillage measures, such as rotary tillage, subsoiling, and no tillage may reduce the shortcomings of traditional long-term farming. To explore the long-term production mode suitable for production of maize in the loess dryland area, a long-term experiment was conducted in Fuping County, Shaanxi Province, from 2013 to 2018. Six farming modes were used in the experiment: no tillage/subsoiling (N ↔ S), subsoiling/rotary tillage (S ↔ R), rotary tillage/no tillage (R ↔ N), continuous no tillage (N ↔ N), continuous subsoiling (S ↔ S), and continuous rotary tillage (R ↔ R). The changes in soil physical and chemical properties, soil water use patterns, soil water storage, conservation effects during the fallow and growth period, and the effects on farmland yield increase were analyzed. The results showed that rotary tillage can effectively improved soil structure and reduced soil bulk density, where N ↔ S treatment soil bulk density is low and in 0-60 cm soil layer averaged 1.31 g/cm3. Different tillage treatments could be used during the fallow period to store additional soil moisture: the N ↔ S treatment showed good water storage effect. Compared to traditional tillage, different tillage methods provided better soil moisture conditions for crops during the growth period, where N ↔ S treatment showed good soil moisture status during the growth period of spring maize. Among all the treatments, N ↔ S treatment effectively increased the organic carbon storage in the 0-60 cm soil layer, which was 54.3 t/hm2. Compared with traditional tillage, different tillage treatments effectively increased plant height and dry matter accumulation of spring maize, where N ↔ S treatment was found to be the best. Compared with the traditional rotary tillage model, the N ↔ S treatment significantly increased crop yield and water use efficiency (WUE) in continuous cropping fields of corn, the average yield of spring corn was 9340.2 kg/hm2, and the average WUE was 22.9 kg/(hm2·mm). In summary, for long-term sustainable development, the N ↔ S model is the best rotational tillage mode for continuous maize cropping in loess soil.

[Evaluation of nitrogen loss way in summer maize system under different fertilizer N managements].

The objective of this study was to investigate nitrogen (N) loss from soil-crop systems under different fertilizer N managements, and to provide some suggestions on optimizing fertilizer management practices. The experiment was carried in high yield production area of Huantai county in Shandong province in 2009. Four kinds of fertilizer N application practices were designed, including CK, farmer practice (FP), optimizing fertilizer application (OPT) and controlled release fertilizer (CRT) for studying the fate of N during the maize growth season in 2009. The water and nitrogen management model (WNMM) was used to simulate the dynamics of soil water and N fate. The results indicated that the ratio of nitrate leaching and NH3 volatilization accounting of fertilizer N ranged from 6% to 18% and 5% to 34%, and their means were 12.7% and 20.7%, respectively. The amount of N leaching under OPT was 14.5 kg x hm(-2), was the lowest in all treatments. The amount of NH3 volatilization under CRT was 7.6 kg x hm(-2), respectively, was the lowest in all treatments. The order of total N loss under four treatments followed as: FP > OPT > CRF approximately CK. Both OPT and CRT treatments are the best management practices considering their high grain yield, water and nitrogen use efficiencies, and environmental protection.