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5×104 kg·hm-2 . In the second and third years, 4.5×104 kg·hm-2 straw returning had the highest average yield of tomato, which was 92.50 and 107.75 t·hm-2, respectively. The maximum WUE was observed with the straw returning of 1.5×104 kg·hm-2 in A1 and A2, while in the A3 treatment it happened in straw returning of 4.5×104 kg·hm-2. The quality index of tomato showed different trends with the increases of straw returning years and amount.To evaluate the applicability of AHC (agro-hydrological chemical and crop systems simulator) model and explore the suitable irrigation amount for peanut (Arachis hypogaea) under mulched drip irrigation in the semi-arid areas of northwestern Liaoning Province, based on the two-year field experimental data of peanut in 2016 and 2017, the model parameters were firstly chosen for global sensitivity analysis. Then, module parameters of soil moisture and crop growth were calibrated and validated. Finally, AHC model was used to analyze the responses of peanut yield and water use efficiency (WUE) to different irrigation amounts. The results showed that the two extremely sensitive parameters of the model were saturated hydraulic conductivity in the first and second layers of soil. Root mean square error (RMSE) and mean relative error (MRE) between simulated and measured values of soil water content ranged from 0.02 to 0.03 cm3·cm-3 and 1.5% to 2.3%, respectively. The RMSE and MRE of leaf area index and plant height were 0.3-0.6, 4.2-4.5 cm, and 5.0%-8.9%, 5.2%-6.8%, respectively. The MRE of peanut yield and water consumption were both within 5%, indicating that the model was suitable for simulating soil moisture and peanut growth in the northwest Liaoning Province. With the increases of irrigation amounts, peanut yield increased and water use efficiency decreased. Considering both peanut yield and WUE, we recommend that the optimal mulched drip irrigation amounts for peanut in the semi-arid areas of Northwestern Liaoning in test year (normal year) was 80-97 mm.Maize stalk mulching is a conservation tillage method that has been currently promoted in northeastern China Plain. Remote sensing estimation of regional crop residue cover (CRC) can quickly obtain the information of straw mulching in a large area, which plays an important role in monitoring and popularizing the work of straw mulching. In this study, the normalized difference til-lage index (NDTI), simple tillage index (STI), normalized difference residue index (NDRI), and normalized difference index 7 (NDI7) were extracted from Sentinel-2A image and used to establish a linear regression model for CRC and spectral indices in Lishu County of Jilin Province. The results showed that soils had strong spatial heterogeneity in the study area, which would lead to a significant impact on the spectral index regression model. Using soil texture classification (zoning) to establish regression model could improve the inversion accuracy. Soil spatial heterogeneity would increase the estimation error of the model. The four spectral indices had a strong correlation with CRC, among which the NDTI and STI models performed better. The zonal linear regression model based on NDTI and STI verified that R2 was 0.84 and RMSE was 13.3%, which was better than the non-zonal model (R2 was 0.75 and RMSE was 16.5%) and thus effectively improved the inversion accuracy.Based on a 9-year field experiment, soil samples under straw mulching (SM), plastic film mulching (FM) and no mulching (CK) were incubated at 15, 25 and 35 ℃ for 60 d to investigate the responses of soil respiration to warming and its temperature sensitivity. The results showed that during the whole incubation period, soil respiration rate exhibited a unimodal distribution, while the cumulative soil respiration increased with an "S" curve. The cumulative soil respiration during the first 30 d accounted for about 75%-85% of total during the whole incubation period. The cumulative SM increased by 19.4% compared with CK, whereas no difference was detected between CK and FM. At 25 ℃ and 35 ℃, the mean soil respiration rate increased by 17.0% and 36.8%, and the cumulative CO2 release of soil respiration increased by 13.1% and 33.6%, respectively, compared with 15 ℃. No interaction was detected between mulching method and temperature. 97.7%-99.9% of variation in soil respiration could be explained by temperature change, with soil respiration being positively correlated with organic carbon and total nitrogen content. Compared with no mulching and plastic film mulching, straw mulching could significantly promote soil respiration by increasing the input of organic matter in the soil, but reduced the temperature sensitivity of soil respiration. Straw mulching rather than plastic film mulching would be more efficient at reducing CO2 emission in the Loess Plateau dryland farming area under the context of global warming.Straw mulching and subsoiling can protect soil and improve soil structure. selleck inhibitor However, long-term continuous subsoiling cannot continuously gain yield increasing and soil improvement. To realize continuous soil improvement and yield enhancement, a long-term experiment on subsoiling alternation patterns was carried out with spring maize continuous cropping in the Loess Plateau in 2007-2016. The subsoiling alternation patterns were no-tillage/conventional tillage/subsoiling (NT/CT/ST) and subsoiling/conventional tillage (ST/CT), with continuous subsoiling (ST) as control. We analyzed the effects of the different patterns on soil physical and chemical properties and maize yield. The results showed that, compared with the ST, the mechanical-stable aggregates (DR0.25) and water-stable aggregates (WR0.25) in NT/CT/ST were significantly increased by 9.2% and 21.9%, with the mean weight diameter (MWD) and geometrical mean diameter (GMD) being significantly increased. The WR0.25 in ST/CT was significantly increased by 11.9%. In 0-20 cm soil layer, soil bulk density in NT/CT/ST and ST/CT decreased by 7.0% and 11.5%, and soil porosity increased by 8.4% and 13.9%, respectively. In 20-40 cm soil layer, soil bulk density in ST/CT increased by 6.9%, and soil porosity decreased by 5.7%. In the NT/CT/ST, soil total nitrogen and organic matter contents significantly increased, but soil total phosphorus and total potassium contents reduced. The multi-year average grain yield of spring maize in NT/CT/ST was 10.2% higher than ST and 4.8% higher than ST/CT. The DR0.25, WR0.25, soil total nitrogen content and soil organic carbon content were all positively correlated with maize yield, indicating such changes faci-litated corn grain yield. Considering the effects on soil fertility and corn yield, the NT/CT/ST model was conducive to soil fertility, soil structural stability and higher maize yield.
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