An improved understanding of the effect of conservation tillage on soil physicochemical quality indicators is obligatory to manage and conserve soil in a climate change scenario. Tillage strategies change soil physicochemical characteristics, consequently modifying crop yields. Conservation tillage is generally used to improve the soil physicochemical characteristics globally. However, the impact of conservation tillage on different soil depths under wheat cultivation is not well documented. A 3-year study was conducted using a randomized complete block design (RCDB). The objective of this research was to specifically study soil physicochemical indicators (soil bulk density, porosity, hydraulic conductivity, water content, temperature, nitrogen, phosphorous, potassium, C:N ratio, pH) and (crop yield) in conventional tillage (CT), straw incorporation into the conventionally tilled soil (CTS), no-tillage (NT), and stubble-retention to the no-tilled soil (NTS) measures under wheat monocropping system across different soil layers. Averaged over 0–40 cm soil layer, the results depicted scarce differences among the tillage practices regarding soil bulk density, porosity, water content and hydraulic conductivity. CT increased soil temperature over conservation tillage systems. Overall, conservation tillage improved soil total nitrogen, available phosphorous, total potassium, C:N ratio and yield than CT, whilst it decreased soil pH. We conclude that NTS and CTS are the best strategies to enhance soil health under wheat mono-cropping system conditions.

Conservation farming practices using the least soil disturbance and straw-return benefits the crop agronomic attributes and soil nutrient accumulation. The four-year (2016-2019) research was conducted under randomized complete blocks design to explore the agronomic benefit of conservation tillage practices on wheat yield performance and on soil fertility parameters. The two straw treatments consisted of wheat straw-return to the notilled soil and straw incorporation into the conventionally tilled soil. The two tillage treatments were the no-tillage and conventional tillage control. These conservative tillage treatments were compared with the conventional tillage control. In comparison with conventional tillage, the conservation management practices of no-tilled soil, conventionally tilled soil, and no-tillage notably increased the yield by an average of 33, 26, and 18% respectively. Moreover, conservative tillage practices improved the soil nitratenitrogen, ammonium nitrogen and carbon contents in the 0-30 cm soil layer by 12, 9, and 15% respectively over conventional tillage, averaged across conventionally tilled soil, no-tilled soil, and no-tillage. The overall distribution of soil nitrate-nitrogen, ammonium nitrogen, and carbon in the 0-30 cm soil layer with regard to conventionally tilled, no-tilled soil, and no-tillage was greater than conventional tillage, based on Principal Component Analysis. We concluded that conservation tillage practices could replace conventionally tilled practice with respect to productivity, soil mineral nitrogen, and carbon accumulation benefits. K e y w o r d s: agronomic traits, conservation agriculture, soil mineral nitrogen, no-till, C dynamics

As one of the important greenhouse gas, nitrous oxide (N2O) has attracted much attention globally under climate change context. Agricultural practices are the main sources of greenhouse gas emissions. Nevertheless, scarcity of literature is available on the effects of different tillage measures on soil N2O emission under spring wheat (Triticum aestivum L.) ecosystem in the semi-arid area of the Loess Plateau. The main objective of the experimental study was to explore the influence of conservation tillage techniques on soil physicochemical properties, nitrous oxide emission and yield in the Northern semi-arid Dingxi region of China. Four treatments viz., conventional tillage (CT), no tillage (NT), straw mulch with conventional tillage (TS) and stubble-return with no-till (NTS) were evaluated under randomized complete block design with three replications. Our results depicted that compared with conventional tillage, bulk density and water content of topsoil was increased and soil pH value was reduced under conservation tillage techniques. Conservation tillage NT, TS and NTS increased organic carbon, TN, MBN and NH4+-N and reduced the accumulation of NO3–N. Additionally, although the N2O emission under NT, TS and NTS was 8.95, 41.90 and 21.05% respectively higher than under T treatment, the corresponding wheat yield was 15.40, 31.97 and 63.21% higher than T treatment. Moreover, correlation analysis showed that soil moisture and temperature were the most significant factors affecting soil N2O emission. The NTS treatment pointedly increased crop yield without significantly increasing soil N2O emission. Consequently, based on economic and environmental benefits and considering N2O emission and crop yield, we suggest that NTS technique is the best conservation tillage strategy in the semi-arid environmental zone of the Loess Plateau of Dingxi China.

The influence of tillage and nitrogen fertilization methods on soil quality attributes and crop agronomic characteristics has been studied broadly under different agroclimatic conditions. Nevertheless, the interactive effect of tillage and fertilization approaches on soil properties on different soil depths and yield is rarely addressed, particularly on the Loess Plateau belt, and requires more exploration. Thus, this research was conducted in order to evaluate the interactive impact of tillage and nitrogen fertilization methods on soil properties and wheat productivity. The treatments included conventional tillage (CT) and no-till (NT) with different fertilization approaches (no fertilization: CK, chemical nitrogen fertilizer: N, organic fertilizer: M, combined application of nitrogen fertilizer and organic fertilizer: NM) and were explored in a split plot arrangement under a randomized complete block design replicated thrice on soil properties (SWC, SOC, TN, TP, NO3−-N, NH4+-N, and stoichiometric ratio) and wheat yield. The results showed that sole no-tillage and NT in association with nitrogen fertilization (inorganic and organic) significantly increased the soil water content, SOC, TN, NH4+-N, C/P, and N/P ratios and wheat productivity but did not significantly yield TP, whilst it reduced the NO3−-N and C/N ratio compared with sole CT and CT together with nitrogen fertilization (organic and inorganic). Overall, NT in association with the joint application of inorganic and organic N fertilization are the best techniques to improve soil water status and nutrient status under the wheat mono-cropping system conditions and yield.

Agricultural practices are significant to increase the soil nitrogen and organic carbon sequestration to adapt and mitigate the climate change in a recent climate change scenario. With this background, we carried out research in the Longzhong Loess Plateau region of China. This research was conducted under a randomized complete block design, with three replicates. Adopt the method of combining outdoor positioning field test with indoor index measurement to explore the soil bulk density (BD), nitrogen components (viz., nitrate nitrogen (NO3−-N), ammonia nitrogen (NH4+-N), total nitrogen (TN), microbial biomass nitrogen (MBN) and nitrogen storage (NS), and carbon components [viz., soil organic carbon (SOC), easily oxidized organic carbon (EOC), microbial biomass carbon (MBC) and carbon storage (CS), carbon pool index (CPI), carbon pool activity (A) and carbon pool activity index (AI) and carbon pool management index (CPMI)] and C/N, ratio under different tillage practices [namely., conventional tillage (CT), no tillage (NT), straw mulch with conventional tillage (CTS) and straw mulch with no tillage (NTS)]. Our results depicted that different conservation tillage systems significantly increased soil BD over conventional tillage. Compared with CT, the NTS, CTS and NT reduced soil NO3−-N, increased the soil NH4+-N, TN, MBN and NS, among them, NS under NTS, CTS and NT treatment was 25.0, 14.8 and 13.1% higher than that under CT treatment, respectively. Additionally, conservation tillage significantly increased SOC, EOC, MBC, CS, CPI, AI, CPMI and C/N, ratio than CT. Inside, CS under NTS, CTS and NT treatment was 19.4, 12.1 and 13.4% higher than that under CT treatment, respectively. Moreover, during the 3-year study period, the CPMI under NTS treatment was the largest (139.26, 140.97, and 166.17). Consequently, we suggest that NTS treatment was more sustainable strategy over other investigated conservation tillage practices and should be recommended as climate mitigation technique under climate change context.