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Reductions in soil productivity and soil water retention capacity, and water scarcity during crop growth, may occur due to long-term suboptimal tillage and fertilization practices. Therefore, the application of appropriate tillage (subsoiling) and fertilization (organic fertilizer) practices is important for improving soil structure, water conservation and soil productivity. We hypothesize that subsoiling tillage combined with organic fertilizer has a better effect than subsoiling or organic fertilizer alone. A field experiment in Henan, China, has been conducted since 2011 to explore the effects of subsoiling and organic fertilizer, in combination, on winter wheat (Triticum aestivum L.) farming. We studied the effects of conventional tillage (CT), subsoiling (S), organic fertilizer (OF), and organic fertilizer combined with subsoiling (S+OF) treatments on dry matter accumulation (DM), water consumption (ET), water use efficiency (WUE) at different growth stages, yield, and water production efficiency (WPE) of winter wheat over 3 years (2016–2017, 2017–2018, 2018–2019). We also analyzed the soil structure, soil organic carbon, soil microbial biomass carbon and nitrogen, and soil enzymes in 2019. The results indicate that compared with CT, the S, OF and S+OF treatments increased the proportion of >0.25 mm aggregates, and S+OF especially led to increased soil organic carbon, soil microbial biomass carbon and nitrogen, soil enzyme activity (sucrase, cellulose, and urease). S+OF treatment was most effective in reducing ET, and increasing DM and WUE during the entire growth period of wheat. S+OF treatment also increased the total dry matter accumulation (Total DM) and total water use efficiency (total WUE) by 18.6–32.0% and 36.6–42.7%, respectively, during these 3 years. Wheat yield and WPE under S+OF treatment increased by 11.6–28.6% and 26.8–43.6%, respectively, in these 3 years. Therefore, S+OF in combination was found to be superior to S or OF alone, which in turn yielded better results than the CT. [ABSTRACT FROM AUTHOR]

Long‐term conventional tillage leads to soil compaction and formation of a plough layer, which affects soil physical properties, transport of water, and growth of crop roots toward deeper soil, resulting in soil degradation and a decline in crop productivity. Long‐term sub‐soiling tillage has proven to be an effective measure for remediating the plough layer and improving the structure and physical properties of the soil. In this study, we experimentally investigated the effects of long‐term sub‐soiling tillage in an arid region of Henan Province, China, along a deep soil (0–100 cm) profile over 8 years of sub‐soiling tillage at a depth of 30 cm and compared the results against conventional tillage at a depth of 15 cm. We measured soil pore distributions of macropores (> 1 mm in diameter), mesopores (0.16–1.0 mm), and total pores (> 0.16 mm) measured by X‐ray computed tomography (CT), soil total porosity (ϕ) and > 0.16 mm equivalent porosity measured by conventional methods, soil bulk density (ρs), soil organic carbon content (SOC), the proportion of macroaggregates (> 0.25 mm) (PMA), soil field moisture capacity (fc), available moisture content, and saturated hydraulic conductivity (Ksat). The results indicate that long‐term sub‐soiling tillage increased soil pore numbers at 0–35 cm depth (macropores, mesopores, and total pores), improved pore shape, and significantly increased porosity at 0–20 cm depth (macropores, mesopores, and total pores; p < 0.05) compared to conventional tillage. In addition, ϕ and > 0.16 mm equivalent porosity were increased by 10.4 and 87.1% at depths of 0–60 cm under sub‐soiling tillage, respectively. SOC (0–55 cm depth), fc (0–45 cm depth), available moisture content (0–40 cm depth), Ksat (0–40 cm depth), and PMA (0–50 cm depth) were increased by 16.7, 14.3, 23.8, 471.5, and 98.3%, respectively, and ρs (0–60 cm depth) was reduced by 8.6%. Observed correlations between SOC, soil pore parameters, and soil physical properties suggest that soil pore parameters and soil physical properties can be improved by increasing SOC. These correlations are stronger under sub‐soiling than that under conventional tillage. Therefore, sub‐soiling is an effective technique for improving soil pore characteristics and physical properties while preventing soil degradation. [ABSTRACT FROM AUTHOR]

No-tillage (NT) is considered being a beneficial soil management regime because of its potential to minimize the detrimental impact of agriculture on the environment and increase crop yield. The nitrogen (N) dynamics and crop growth were significantly affected when NT is alternative to conventional tillage (CT). However, the long-term effects of NT on N dynamics especially uptake and utilization and crop growth are not well understood. The aim of this study was to quantify the N cycle in the 0–100 cm soil profile, as well as the total N uptake and yield of winter wheat (Triticum aestivum L.) when the soil management changed from CT to NT for years. To this end, a 7-year field experiment was conducted from 2010 to 2017 on a sandy loam soil in Henan Province, China. Soil organic carbon, soil water and inorganic nitrogen content, plant growth and yield collected in field experiment were used to calibrate and validate the root zone water quality model. The simulated results indicated that a 55.8% decrease in N leaching, 4.8% increase in soil available N and 3.4% increase in averaged root N uptake when the soil management switched from CT to NT. Additionally, the average grain yield, N use efficiency, N utilization efficiency and N harvest indices were all improved under NT. Therefore, replacing CT with NT appears to be beneficial in terms of reducing N pollution of groundwater, enhancing N availability and wheat production. [ABSTRACT FROM AUTHOR]

• Studying dynamics of soil water and nitrogen balance under conventional tillage versus conservation tillage by using RZWQM model. • Quantifying the winter wheat yield, water productivity and NUE under conventional tillage versus conservation tillage by using RZWQM model. • Establishing no-tillage as the optimum tillage to replace the conventional tillage for a sandy loam soil in Henan Province of China. The movement and distribution of the soil water and nitrogen are significantly influenced by tillage management. However, the dynamics of soil water and nitrogen due to changes in tillage and surface residue cover can be difficult to characterize due to limitations in field experimentation. The objective of this study was to quantify the differences in the soil water and nitrogen balance in the 0–100 cm soil profile, winter wheat (Triticum aestivum L.) yield, water productivity (WP) and nitrogen use efficiency (NUE) that occur when conventional tillage (CT) was changed to four types of conservation tillage treatments (no-tillage [NT], subsoiling tillage [ST], no-tillage with straw [NS] and subsoiling tillage with straw [SS]). Experimental data from 2011 to 2016 collected in Henan province, China on a sandy loam soil was used to calibrate and validate the Root Zone Water Quality Model (RZWQM2). Then the model was used to simulate four tillage systems (NT, NS, ST, SS) that were then compared with CT. The agreement index (d) between simulated and measured soil water content, soil nitrate concentration, and grain yield ranged between 0.71 and 0.93. The root means square error (RMSE) of the soil water content and nitrate concentration was in the range 0.02–0.03 cm cm−1and 5.5–10.3 mg kg−1, respectively. When CT was converted to NT from 2011 to 2016, the model simulated a 9.1 % reduction in annual water loss and a 55.6 % decrease in nitrogen leaching loss and simulated significant increase in average grain yield, WP and NUE. Replacing CT with NT appears to be the best of the four alternative conservation tillage conversion strategies in Henan Province of China. [ABSTRACT FROM AUTHOR]