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Deep fertilization is a beneficial approach for reducing nitrogen losses. However, the effects of various fertilization depths on maize (Zea mays L.) productivity and environmental footprints have not been thoroughly understood. Therefore, a field experiment was conducted to investigate the effects of different fertilization depths of 5 cm (D5), 15 cm (D15), 25 cm (D25), and 35 cm (D35) on maize productivity and environmental footprints. Reactive nitrogen (Nr) losses and greenhouse gas (GHG) emissions were assessed using life cycle analysis. We hypothesized that deep fertilization can obtain lower carbon and nitrogen footprint. The results indicated that deep fertilization decreased the N2O and NH3 emissions while increasing the CH4 uptake. Compared with D5, D15 resulted in an increase in total GHG emissions and carbon footprint (CF), whereas D25 decreased by 13.0% and 23.6%, respectively. Compared with D5, the Nr losses under D15, D25, and D35 conditions was reduced by 11.3%, 17.3%, and 21.0%, respectively, and the nitrogen footprint (NF) was reduced by 16.0%, 27.4%, and 19.0%, respectively. The maize yield under D15 and D25 increased by 5.7% and 13.8%, respectively, compared with the D5 treatment, and the net economic benefits of the ecosystem increased by 7.1% and 17.1%, respectively. In summary, applying fertilizer at a depth of 25 cm can significantly reduce the environmental footprints and increase maize productivity, making it an effective fertilization strategy in the Loess Plateau region of China. [ABSTRACT FROM AUTHOR]

Studying carbon dioxide fluxes in wheat fields is becoming increasingly important. The dry semi-humid area in China is an important wheat production area, but the variations in carbon dioxide fluxes in wheat fields and the mechanisms associated with the carbon dioxide flux response to meteorological factors and water-nitrogen management have rarely been studied systematically in this area. Thus, we conducted a monitoring experiment in order to clarify the responses of CO2-C fluxes to meteorological factors and water-nitrogen management in wheat fields in this dry semi-humid area, and modeled the relationships between CO2-C fluxes and meteorological factors under different water-nitrogen managements. Four water-nitrogen treatments were tested in wheat fields: rain-fed (no water and nitrogen added), irrigation (150 mm water added), rain-fed plus nitrogen application (225 kg ha−1 nitrogen added), and irrigation plus nitrogen application (150 mm water and 225 kg ha−1 nitrogen added). The CO2-C fluxes and meteorological indicators were monitored and analyzed, before fitting the relationships between them. The direct and total effects of precipitation, air temperature, and water vapor pressure on CO2-C fluxes in wheat fields were all positive, and their total effect coefficients were more than 0.7 and significant. Irrigation and nitrogen application increased the CO2-C fluxes in wheat fields by 6.82–14.52% and 51.59–55.94%, respectively. The fitting results showed that partial least squares regression models of the relationships between meteorological factors and CO2-C fluxes in wheat fields under different treatments were all effective, with R2Y (cum) and Q2 (cum) values around 0.7. Overall, these results suggest that precipitation, air temperature, water vapor pressure, and water and nitrogen addition have positive effects on CO2-C fluxes from wheat fields in dry semi-humid areas. The partial least squares regression method is also suitable for modeling the relationships between meteorological factors and CO2-C fluxes. These results may provide a scientific basis for predicting and regulating CO2-C fluxes in wheat fields in dry semi-humid areas, and provide a methodological reference for ecosystem carbon dioxide flux simulation studies. [ABSTRACT FROM AUTHOR]

Soil aggregation plays a critical role in the maintenance of soil structure and crop productivity. Fertilization influences soil aggregation, especially by regulating soil organic carbon (SOC) and total nitrogen (TN) contents in aggregate fractions. Here, we conducted a fixed-site field experiment to quantify the effect of five N application rates: 0, 75, 150, 225, and 300 kg·N·ha−1, denoted as N0, N75, N150, N225, and N300, respectively, on soil aggregate stability, aggregate-associated SOC and TN sequestration and crop productivity. Soil aggregates were divided into >0.25 (>5, 5–2, 2–1, 1–0.5, 0.5–0.25) and <0.25 mm through wet and dry sieving methods. The results showed that long-term fertilization increased the proportion of macro-aggregates (>0.25 mm), decreased the proportion of micro-aggregates (<0.25 mm), and improved the aggregates stability. Compared with N0, the proportion of micro-aggregates in N225 was significantly decreased by 66.45% under wet sieving, while the proportion of >5 mm macro-aggregates in N225 was significantly increased by 19.24% under dry sieving (p < 0.05). With the increase in N application rate, the bulk SOC and TN contents first increased and then decreased, and the SOC and TN of N225 were significantly increased by 17.75% and 72.33% compared with N0 (p < 0.05). More specifically, fertilization promoted the distribution and enrichment of SOC and TN in macro-aggregates and reduced the C/N of the micro-aggregates and the contribution of SOC and TN in the micro-aggregates. Compared with N0, the contribution rate of macro-aggregates to SOC and TN of N225 under wet sieving was significantly increased by 84.13 and 17.18%, respectively, while the C/N of micro-aggregates of N225 under wet and dry sieving methods was significantly decreased by 45.95 and 31.74%, respectively (p < 0.05). Moreover, fertilization improved the yield, and N225 significantly increased the total yield by 80.68% compared with N0 (p < 0.05). In conclusion, N225 was the suitable N application for improving soil aggregate stability, carbon and nitrogen sequestration, and crop productivity on the Loess Plateau, China. [ABSTRACT FROM AUTHOR]

The ridge and furrow rainfall harvesting planting system (RFRHP) where runoff is collected by plastic mulched ridges can improve the crop productivity in the semiarid areas of northwest China. During 2012–2014, we performed a field evaluation of the influence of RFRHP with supplementary irrigation (RI) on the water irrigation use and water use efficiency by maize in a semiarid climate using the following treatments: (1) no supplementary irrigation (RN); (2) irrigation during the trumpeting stage (RB); (3) irrigation during the blooming stage (RF); (4) irrigation during the trumpeting and blooming stages (RBF); and (4) traditional flat planting with border irrigation (CK). We found that although the irrigation volume was double under CK, the soil water content in the 0–120 cm soil layer did not differ significantly between the RFRHP with supplementary irrigation treatments and CK. The RFRHP with supplementary irrigation treatments reduced the irrigation water volume required (750–1125 m3 hm−2) and alleviated drought stress during key maize growth periods. The biomass, grain yield, and water use efficiency were significantly higher under RFRHP with supplementary irrigation, i.e., 6.0–8.7%, 15.4–25.8%, and 34.9–39.2% higher compared with CK, respectively, and 3.8–6.4%, 4.8–14.2%, and 9.2–12.7% higher compared with RFRHP with no supplementary irrigation. Under RFRHP with supplementary irrigation treatments, the irrigation water use efficiency was 1.5–3.9 times higher than that under CK. The irrigation water productivity levels under the RFRHP with supplementary irrigation treatments were ranked as follows: trumpeting stage > trumpeting and blooming stages > blooming stage. Compared with CK, RFRHP with supplementary irrigation significantly increased the out/input ratio and net income by 13.1–26.9% and 2600–3762 Chinese Yuan hm−2, respectively. [ABSTRACT FROM AUTHOR]

Deep fertilization strategy has been proven to be an important fertilizer management method for improving fertilizer utilization efficiency and crop yield. However, the relationship between soil chemical and biochemical characteristics and crop productivity under different fertilization depth patterns still needs comprehensive evaluation. Field tests on spring maize were therefore carried out in the Loess Plateau of China for two successive growing seasons from 2019 to 2020. Four distinct fertilization depths of 5 cm, 15 cm, 25 cm, and 35 cm were used to systematically investigate the effects of fertilization depth on soil physicochemical parameters, enzyme activity, and biochemical properties. The findings demonstrated that although adjusting fertilization depths (D15, D25) did not significantly affect the soil organic carbon content, they did significantly improve the soil chemical and biochemical characteristics in the root zone (10–30 cm), with D25 having a greater influence than D15. Compared with D5, the total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), Olsen-P, dissolved organic carbon, and nitrogen (DOC and DON) in the root zone of D25 significantly increased by 12.02%, 7.83%, 22.21%, 9.56%, 22.29%, and 26.26%, respectively. Similarly, the urease, invertase, phosphatase, and catalase in the root zone of D25 significantly increased by 9.56%, 13.20%, 11.52%, and 18.05%, while microbial biomass carbon, nitrogen, and phosphorus (MBC, MBN, and MBP) significantly increased by 18.91%, 32.01% and 26.50%, respectively, compared to D5. By optimizing the depth of fertilization, the distribution ratio of Ca 2 –P and Ca 8 –P in the inorganic phosphorus components of the root zone can also be increased. Therefore, optimizing fertilization depth helps to improve soil chemical and biochemical characteristics and increase crop yield. The results of this study will deepen our understanding of how fertilization depth influence soil properties and crop responses. • Suitable fertilization depth improved the soil biochemical properties. • Changing the fertilization depth regulated the inorganic phosphorus components proportion. • Optimizing fertilization depth (25 cm) contributes to maize yield by matching with the depth of the main root system. [ABSTRACT FROM AUTHOR]

The low precipitation and low soil fertility in the Loess Plateau region of China limit the sustainable development of farmland. No-tillage, straw mulching, or planting green manure can improve soil water storage or soil quality. However, further research is needed to optimize these soil and fertilizer management strategies to maximize yield and effectively utilize resources. The present study aimed to determine the optimal soil and fertilizer management strategies to maximize wheat growth and water/nitrogen utilization efficiency, while minimizing nitrogen fertilizer input. Five different soil and fertilizer treatments were tested on the Loess Plateau between 2009 and 2021, including traditional tillage followed by bare soil (CK), no-till with straw mulching (NTSM), no-till with straw mulching followed by leguminous green manure (OPT), and reductions in N fertilizer inputs of 10% (OPT10) and 20% (OPT20) under OPT. The average results from 12 years of research revealed that the soil water content (SWC) and NO 3 –-N content in the 0–20 cm soil depth under OPT were higher by 4.3% and 13.4% compared to CK (P < 0.01), and the length and surface area of the wheat roots were higher by 20.9% and 11.0% (P < 0.01), respectively. Optimized soil and fertilizer management delayed leaf senescence and enhanced the antioxidant and photosynthetic capacities of the wheat crop. Compared with CK, the net photosynthetic rate and superoxide dismutase activity were 38.6% and 11.6% higher under OPT, respectively, and no significant differences were observed between OPT and OPT10. Optimized soil and fertilizer management promoted wheat yield formation, water and fertilizer use efficiency, and OPT obtained the highest yield (4497.3 kg ha−1), N uptake (138.7 kg ha−1), and water use efficiency (WUE, 13.3 kg ha−1). Compared with CK, OPT increased the wheat yield, N uptake, WUE, and WP by 21.5%, 16.7%, 16.6%, and 12.6%, respectively, and there were no significant differences between OPT10 and OPT. Optimizing the soil and fertilizer management strategies increased the soil water and NO 3 –-N contents, delayed leaf senescence, enhanced the leaf antioxidant and photosynthetic capacities, promoted wheat yield formation and efficient resource utilization. A 10% reduction in N fertilizer input based on no-till, straw mulching and green manure planting during the fallow period is an efficient soil and fertilizer management strategy for ensuring sustainable wheat production in semi-arid areas of the Loess Plateau. Our findings provide a reference for wheat production in semi-arid regions similar to the Loess Plateau throughout the world. • No-till, straw mulching, and planting green manure (OPT) increased soil moisture and NO 3 –-N contents. • The increased soil water and NO 3 –-N contents inhibited wheat leaf senescence. • OPT obtained the highest wheat yield and resource use efficiency. • A 10% reduction in N inputs based on OPT maintained a higher wheat yield and resource use efficiency. [ABSTRACT FROM AUTHOR]

• Precipitation and fertilizer promoted photosynthetic characteristics and grain yield. • Initial soil moisture had greater effect on grain yield than precipitation during growing season. • Fertilizer management can improve food security under changes in precipitation. The ridge and furrow (RF) system can improve the soil moisture and temperature conditions, as well as increasing the grain yield and water use efficiency. However, the combined effects of the fertilizer amount, precipitation during the growing season (PGS), and soil water storage before sowing (SWSS) on the photosynthetic characteristics and yield under this system are still unclear in winter wheat. Thus, in this study, we used path analysis to determine the effects of these three factors based on a field experiment conducted for five years in a semiarid region of Northwest China. Path analysis showed that precipitation during the sowing to filling stage (PSF) in winter wheat had the greatest influence on the photosynthesis gas exchange characteristics of flag leaves in the filling stage, followed by the fertilizer amount. And the determination coefficients of PSF on the photosynthetic rate (Pn), transpiration rate, stomatal conductance (Gs), leaf instantaneous water use efficiency (WUE) and relative chlorophyll content (SPAD value) were 0.331, 0.868, 0.864, 0.820, and 0.414, respectively. The most important factor for the grain yield was SWSS, where the coefficient of determination was 0.838, followed by the fertilizer amount and PGS, and the indirect effect of the fertilizer amount on SWSS was negative. Therefore, our results suggest that SWSS has an important effect on the grain yield in winter wheat under the RF system in semiarid regions, and thus improving the SWSS can obtain better increases in the grain yield compared with fertilizer amount. [ABSTRACT FROM AUTHOR]

• RFMS promoted photosynthesis by improving soil hydrothermal conditions. • RFMS shortened vegetative growth but prolonged reproductive growth. • RFMS positively affected the dynamics and allocation of key production resources. • RFH was more efficient at using resources than RFL. Utilizing ridge-furrow construction combined with plastic film mulching system (RFMS) is an effective strategy for improving crop productivity in semi-arid areas. However, the key mechanisms by which RFMS stimulates the integrated utilization of key production resources (thermal, water and radiation) to affect maize production is not well-defined. In the Loess Plateau of China, three treatments were applied in a two-year field experiment: 1) RFH with RFMS at a high coverage ratio (50 cm mulched ridge:10 cm unmulched furrow); 2) RFL with RFMS at a low coverage ratio (60 cm mulched ridge:60 cm unmulched furrow); and 3) FP as the control without mulching. RFMS significantly improved soil hydrothermal conditions, which enhanced photosynthesis and promoted canopy growth to intercept more radiation. With an increase of soil thermal time (TT soil) by 199.1–415.1 °C d compared with FP, the thermal effect of RFMS improved maize crop phenology by shortening the duration of vegetative stage to prolonging reproductive stage by 1–3 days, thereby prioritizing the allocation of the captured radiation, thermal and water to reproductive growth. These alterations significantly increased maize grain yield by 38.0–59.6%, and enhanced the efficient use of resources by 13.7–21.9% in thermal, 34.6–59.8% in water and 30.0–50.0% in radiation, which enhanced when increasing coverage (RFH vs. RFL). Overall, these alterations of RFMS on hydrothermal, as an adaptive strategy, can positively mark the capture and allocation of resources and the conversion of resources into biological materials (especially grains) in semi-arid areas like the Loess Plateau. [ABSTRACT FROM AUTHOR]

Highlights • Exploiting winter wheat productivity and radiation use efficiency through ridge furrow system and supplemental irrigation. • Ridge and furrow with plastic film system have positive effect on improve LAI, radiation use efficiency and grain yield. • Simulated rainfall (200 mm) with 150 mm supplemental irrigation under ridge furrow system was appropriate. • Thus, it increased the yield, LAI and radiation use efficiency. Abstract Agricultural productivity in semi-arid regions of China relies on the ridge furrow (RF) micro rainfall harvesting system, and supplemental irrigation reduces damage caused by drought stress. However, the extent to which the interactive effects of supplemental irrigation and simulated rainfall conditions can further improve winter wheat production and radiation use efficiency (RUE) remains unknown. Therefore, a mobile rainproof shelter was used to explore the potential benefit of the RF system under four supplemental irrigation (150, 75, 37, 0 mm) levels and three simulated rainfall (275, 200, 125 mm) levels. Data collected over two years indicated that the interactive effects of supplemental irrigation (150 mm) with simulated rainfall concentration (200 mm) could significantly improve the LAI (88.8%), Pn value (21.3%), PAR interception efficiency (I n ; 34.1%), interception of PAR accumulation (IPAR) (58.9%), RUE (11.2%), and PAR capture ratio (97.1%), due to reduction in the PAR reflection ratio (45.2%), canopy light transmittance (LT) (78.5%), and PAR penetration ratio (83.8%), and significantly increase the grain yield (60.0%) as compared to that of the RF3 150 treatment. Consequently, this RF system significantly improved the grain yield, with earlier development and rapid plant growth during each growth stage of winter wheat, at each supplemental irrigation and simulated rainfall level. The results suggest that in semi-arid regions of China, where water shortage is a serious problem, the RF2 150 treatment should be adopted as standard farming practice for improving crop growth, LAI, photosynthesis, efficient conversion of intercepted solar radiation by apical dominance, IPAR, RUE, total DMA, and winter wheat production. [ABSTRACT FROM AUTHOR]

Lodging stress significantly reduces the grain yield and quality. Uniconazole is a plant growth regulator and it can potentially reduce lodging stress by enhancing lignin metabolism and lodging resistance. We conducted a field study in the semiarid regions of China to determine suitable uniconazole application strategies based on the culm morphological characteristics, rind penetration strength, lignin metabolism, lodging stress, and grain yield from summer maize during 2015 and 2016. Seeds were soaked in uniconazole at concentrations of 0 (SCK 0 ), 25 (SU 25 ), 50 (SU 50 ) and 75 (SU 75 ) mg kg −1 . In another experiment, uniconazole was applied to the foliage at concentrations of 0 (FCK 0 ), 25 (FU 25 ), 50 (FU 50 ) and 75 (FU 75 ) mg L −1 at the eight-leaf stage. Our results suggested that uniconazole significantly alleviated lodging stress by enhancing lignin metabolism and optimizing the culm morphological characteristics. Uniconazole significantly increased the lignin content and activities of lignin-related enzymes such as phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, tyrosine ammonia-lyase, and peroxidase, where their maximum values were obtained with SU 25 and FU 25 treatments. The grain yield and ear characteristics increased but then decreased as the uniconazole concentration increased, where treatments SU 25 and FU 25 obtained the highest grain yield and ear characteristics. Seed soaking significantly enhanced lignin accumulation and alleviated lodging stress compared with foliar application. Our results suggest that the lignin content is closely related to lodging resistance in maize and higher lignin accumulation in the third basal internode can improve lodging resistance. Uniconazole application significantly reduced the risk of lodging stress and improved the grain yield of maize, where the most effective treatments were soaking seeds at 25 mg kg −1 and foliar application of 25 mg L −1 at the eight-leaf stage. [ABSTRACT FROM AUTHOR]

The soil quality is poor in the arid areas of Northwest China and planting green manure can improve the soil quality but it also increases the soil water consumption. Straw mulching in the wheat (Triticum aestivum L.) fallow season can improve the soil water content. It is unclear whether green manure can be planted in addition to straw mulching to improve the soil water content and quality. Therefore, a field experiment was conducted in the semi-arid area of the Loess Plateau in China from 2009 to 2017 with the following treatments; (1) traditional bare land in fallow season after plowing (CK), (2) no-tillage with straw mulching (NTSM), (3) and no-tillage with straw mulching and planting soybean as green manure (NTSGM). We determined the effects of these three treatments on the soil water, nutrients, and wheat productivity. Compared with CK, the average soil water contents in 0–100 cm soil depth increased by 11.1% and 3.6% under NTSM and NTSGM, respectively, during the soybean full bloom stage, and by 13.06% and 6.6% before wheat sowing. Compared with CK, the decomposition of green manure increased the NO 3 –-N contents in the 0–100 cm soil depth by 6.6% and 5.3% under NTSGM before wheat sowing and after harvesting, respectively, and NTSM and NTSGM significantly improved the soil nutrients, microbial biomass contents, and enzyme activities. The superior soil quality and water content under NTSM and NTSGM increased the fertilizer uptake and partial factor productivity. Compared with CK, the average precipitation storage efficiency, water use efficiency during the whole year, biomass, and wheat yield were 32.6%, 23.2%, 16.2%, and 21.6% higher under NTSGM, respectively. Therefore, NTSGM is an effective method for improving the soil water storage and NO 3 –-N contents before sowing wheat, as well as the water use efficiency, soil quality, utilization of nutrients, and wheat productivity in semi-arid areas of the Loess Plateau. • No-tillage and straw mulching in the fallow season significantly increased the soil water content. • Planting green manure significantly improved the soil nutrient contents. • Plow layer management during the fallow season enhanced the utilization of resources and wheat productivity. • Water consumed by green manure can be compensated for by straw mulch and no-tillage. • This plow layer management strategy can be used during the fallow season in semi-arid areas. [ABSTRACT FROM AUTHOR]

It is important to assess the potential uptake of methane (CH 4) in dryland farming and its contribution to global warming mitigation by elucidating the migration characteristics of CH 4 in the soil profile. Therefore, before planting spring maize in the Loess Plateau region of China in 2019–2020, we applied fertilizer at soil depths of 5, 15, 25, and 35 cm (D5, D15, D25, and D35, respectively). The uptake of CH 4 and diffusion flux were determined simultaneously in the soil surface and profile. We found that the dryland soil was a sink for CH 4 and the cumulative CH 4 uptake amount by soil without fertilization during the maize growth stage was 1.54 kg ha–1. Fertilization inhibited the uptake of CH 4 by the soil, but deep fertilization promoted its uptake. The cumulative surface CH 4 uptake amounts under D15, D25, and D35 were significantly higher than that under D5, i.e., by 42.4%, 105.6%, and 169.1%, respectively. The CH 4 concentration and diffusion flux decreased as the soil depth increased, and CH 4 diffused downward in the soil profile. The CH 4 consumption rate was greater than the production rate in the 0–20 cm soil layer, whereas the opposite was found in the 20–30 cm layer. The surface CH 4 uptake flux was significantly positively correlated with the diffusion flux in the 0–30 cm soil layer. Inorganic nitrogen (N) inhibited the diffusion of CH 4 from the surface through the soil profile and its diffusion within the profile. The highest maize yield and biomass were obtained under D25. Therefore, increasing the fertilization depth can promote the uptake of CH 4 by the soil in maize fields to alleviate climate change, and a fertilization depth of 25 cm is suitable for balancing the requirements for environmental protection and agricultural production. Our findings provide important insights into the production, consumption, diffusion, and uptake of CH 4 in dryland farming areas. • CH4 production/consumption and diffusion in the vertical soil profile, and surface uptake quantified simultaneously. • Consumption and production of CH4 occurred mainly in 0–20 and 20–30 cm soil layers, respectively. • Dryland is a net CH4 sink and deep placement fertilizer enhances CH4 uptake. • N input inhibits the uptake, diffusion, and transformation of CH4. • Chamber measurement coupled with the gradient method can improve estimates of the CH4 flux. [ABSTRACT FROM AUTHOR]

In dryland farming, maize (Zea mays L.) and peanut (Arachis hypogaea L.) intercropping has been widely practiced to achieve sustainable agriculture goals. However, only a few studies have investigated the effect of reducing nitrogen (N) application on the performance of maize and peanut crops in intercropping system based on rotation of the planting strip. Therefore, a field study was conducted from 2018 to 2020 in Yangling, China, where the treatments comprised peanut monoculture, maize monoculture, maize–peanut intercropping, maize–peanut rotational intercropping, and maize N reduction based on the rotational intercropping system. The N accumulation and yield in maize increased after intercropping, while the N accumulation, yield and N fixation capacity of peanut decreased than other treatments. In addition, soil residual N, ammonia volatilization, N leaching, and N 2 O emissions of maize–peanut intercropping significantly decreased than maize monoculture. The rotation of planting strips in maize–peanut intercropping had increased the land equivalent ratio by 3.06 % and 9.39 % and N recovery efficiency by 15.45 % and 27.37 % in the second and third years of planting, as well as alleviated the continuous cropping barrier for peanuts. N reduction does not affect N fixation capacity and yield of peanut and reduces ammonia volatilization and N leaching from farmland, although it does influence maize yield. The optimal cropping system was a 20 % N reduction in maize planting strip under rotational intercropping because N accumulation and the farmland productivity were not affected significantly, while the N losses to the environment also decreased by an average of 44.17 % and 14.87 % compared with traditional intercropping and monoculture in the second and third years of planting. These results are useful for optimizing cropping systems to promote sustainable development in dryland regions and mitigate N pollution. • Maize-peanut intercropping in dry farming can reduce apparent N loss. • The intercropping N advantage tended to decrease with prolonged experiment duration. • Rotation of planting strips increase the N accumulation and N fixation in peanut. • The marginal benefits were affected by the N application rate. • 20 % N reduction in maize can reduce N-stress of farmland without affecting yield. [ABSTRACT FROM AUTHOR]

An undeveloped root system generally leads to low water utilization efficiency and decreases the yield in spring maize (Zea mays L.). Little is known about whether changing the fertilization depth can optimize the root distribution to improve the water productivity and maize yield. During 2019 and 2020, we conducted a field experiment with spring maize and applied the fertilizer at different soil depths of 0.05 m (D5), 0.15 m (D15), 0.25 m (D25), and 0.35 m (D35) to clarify the regulatory effects of the fertilization depth on the root distribution, water productivity at the biomass level (WP b), and maize yield formation. Compared with D5, D25 significantly increased the root length density of the vertical roots, inter-row roots, and within-row roots in the 0–1.0 m soil depth by 18%, 14%, and 24%, respectively, and the root surface area density increased by 39%, 17%, and 22%. Compared with D5, D25 significantly increased the soil water consumption by 28 mm during the maize jointing to silking stage and reduced the soil water content in the 0.4–1.4 m soil depth at the maize silking stage. D25 and D15 also significantly increased the root sap production rate and NO 3 –-N and NH 4 +-N concentrations in the root sap compared with D5 and D35 after the maize silking stage. The N uptake and nitrogen use efficiency under D25 were 17% and 39% higher, respectively, compared with D5. The water productivity at the grain yield and biomass level, biomass, and maize yield values under D25 were 23.5 kg ha–1 mm–1, 45.7 kg ha–1 mm–1, 24320 kg ha–1, and 12477 kg ha–1, respectively, which were 10%, 12%, 13%, and 14% higher compared with D5. The different fertilization depths explained 91%, 86%, and 66% of the variations in the maize yield, N uptake, and total evapotranspiration, respectively. Therefore, deep fertilization at a suitable soil depth regulated the distribution of the root system, which improved the capability of soil water and nitrogen utilization, and eventually increased the water productivity and maize yield. The most effective fertilizer depth was 0.25 m and it can be used as an effective water and fertilizer management strategy for the sustainable development of maize. [Display omitted] • Optimizing fertilization depth to 15 and 25 cm had positive effects on maize productivity. • Optimizing fertilization depth enhanced the root sap production rate and the nitrogen concentration in the root sap. • Optimizing fertilization depth changed the water consumption intensity during different maize growth stages. • Deep fertilization at soil depth of 25 cm most effective in the rainfed area of China. [ABSTRACT FROM AUTHOR]

Deep fertilizer application is an effective strategy for minimizing gaseous losses and improving the nutrient use efficiency and grain yield. However, it is unclear whether deep fertilizer application can improve the antioxidant defense system in maize (Zea mays L.) leaves and the photosynthetic capacity after silking to delay senescence, and then contribute to improvements in the yield and resource utilization efficiency. The effects on the NO 3 –-N residue levels also require elucidation. Therefore, we tested different fertilization application depths in the field during 2019–2020, where all of the N-P fertilizer was applied underground at 5 cm (D5), 15 cm (D15), 25 cm (D25), and 35 cm (D35) before sowing spring maize in the Loess Plateau region of China. The results showed that the antioxidant and photosynthetic performance of the leaves followed the order of: D25 > D15 > D5 > D35. The H 2 O 2 and O 2 – contents decreased by 2 1.5% and 14.0% under D25 compared with D5, respectively, and the net photosynthetic rate (Pn) and mean grain filling rate (G mean) increased by 32.9% and 5.0%. The translocation and assimilation of nitrogen under D25 increased by 20.1% and 18.6% compared with D5, respectively, the translocation and assimilation of phosphorus increased by 43.6% and 54.3%, and the biomass and maize yield increased by 12.7% and 13.8%. The water use efficiency (23.5 kg·ha–1·mm–1), water productivity (45.7 kg ha–1 mm–1), nitrogen use efficiency (43.6%), and phosphorus use efficiency (20.3%) were significantly higher under D25 than the other treatments. The accumulated residual nitrate contents in the 0–100 cm soil layer were 6.0% and 8.0% lower under D15 and D25 than D5, respectively (P < 0.05). However, D35 significantly increased the accumulated residual nitrate content in the 0–200 cm soil depth to increase the risk of leaching. A fertilization depth of 25 cm can delay maize leaf senescence and enhance the grain-filling capability by improving the antioxidant defense system and photosynthetic capacity of the leaves after silking, thereby increasing the maize yield and resource utilization efficiency. • Fertilization depth influenced spatial and temporal distribution of soil NO 3 –-N. • Leaf antioxidant defense system improved with appropriate fertilization depth. • Fertilization depth of 25 cm enhanced maize productivity and resource utilization. • Fertilization depth of 35 cm increased NO 3 –-N residue contents in 0–200 soil layer. [ABSTRACT FROM AUTHOR]

Continuous wheat (Triticum aestivum L.) cropping in the Loess Plateau of China has led to soil degradation and yield reductions. In the present study, we conducted a long-term wheat rotation experiment in Zhenyuan County, Gansu Province, China, between 2005 and 2017, where three cropping systems were tested: (1) continuous winter wheat cropping (W), (2) wheat–wheat–wheat–soybean, i.e., 3 years of wheat and 1 year of soybean (Glycine max L.) rotation (W3–S), and (3) wheat–wheat–wheat–maize, i.e., 3 years of wheat and 1 year of maize (Zea mays L.) rotation (W3-M). Equal amounts of fertilizer were applied to all treatments. All treatments were conducted for four years and repeated three times, with a total of 12 years. Continuous wheat cropping increased the soil bulk density and decreased the soil porosity compared with 2005. However, W3–S and W3-M significantly reduced the soil bulk density and increased the soil nutrients and enzyme activities in 2017 compared with continuous wheat cropping. The average increases in the soil water storage under W3–S and W3-M were 12.7% and 5.9%, respectively. During the wheat growing season, the water use efficiencies under W3–S and W3-M were 22.9% and 12.9% higher, respectively, than that under continuous wheat cropping. The average wheat yields under W3–S and W3-M increased by 25.1% and 14.1%, respectively. Furthermore, according to principal component analysis and correlation analysis, the yield increases were due to the enhanced soil quality, enzyme activities, and water use efficiency. These results suggest that rotation can enhance the soil properties, soil enzyme activity, crop yield, and soil water use efficiency. In addition, wheat–soybean rotation had more positive effects than wheat–maize rotation on the soil quality and crop productivity in the study area. However, wheat was not produced in the fourth year of rotation so the replacement crop would need to be economically viable to facilitate widespread adoption. Further investigation is also required to determine whether the lower biomass production associated with legumes was offset by the increased soil organic carbon during the wheat phase of the rotation. The best rotation method identified in this study may provide a cleaner agronomic production strategy. • Soil bulk density increased under long-term continuous wheat cropping. • Rotation significantly reduced soil bulk density, increased soil porosity, and increased SOC when same inputs applied. • Rotation enhanced soil nutrients and enzyme activities to increase crop yields. • Wheat–soybean rotation had more positive effects on soil quality and crop productivity than wheat–maize rotation. [ABSTRACT FROM AUTHOR]

• N with straw retained increased crop yield. • Excessive N application worsened nitrate N leaching to deep soil layers. • Straw retained improved utilization rate of nitrogen fertilizer. • Straw addition reduced the nitrate N accumulation in the 100−200 cm soil layer. Straw incorporation and nitrogen (N) fertilization are the two important strategies to increase soil fertility and crops productivity, however their improper utilization reduces yield results in environmental pollution and wasting resources. The objective of the experiment was to evaluate the effects of straw incorporation and N fertilization and their interaction on the grain yield, nitrogen resource utilization, nitrate nitrogen (NO 3 −-N) dynamic changes and leaching from 2017 to 2019 in a wheat/maize rotation system in the Loess Plateau region. The experiment consists of two factors; one factor was N rates; 0 (F 0), 150 (F 150), 225 (F 225), 300 (F 300) kg ha-1, and the other factor was straw management; no straw incorporation (–S) and straw incorporation (+S). As a whole there were eight treatments in the experiment. Our results suggested that straw incorporation increased grain and nitrogen uptake, and 150 and 225 kg ha-1 increased grain and nitrogen uptake by 43.6 % and 61.8 % compared with no N fertilization. Increasing N rates gradually decreased the nitrogen recovery efficiency (NRE) and nitrogen agricultural efficiency (NAE). The unutilized N was mainly retained in the soil in the form of nitrate N, and some of the N infiltrates to 100−200 cm soil layer, showing a high N application and high leaching phenomenon, and straw incorporation effectively prevented nitrate N infiltration, and increased the nitrate N content of 0−100 cm in the middle and late stages of maize growth. Based on normalization and fitting results of yield and nitrate N accumulation in 100−200 cm soil layer, we also comprehensively evaluated the effects of N application and straw management on grain yield and environmental benefits. [ABSTRACT FROM AUTHOR]

• The ridge furrow system with border irrigation has significantly increase soil water storage and water use efficiency. • Exploiting of ET, wheat production and seed filling rate under ridge furrow system with deficit irrigation. • 75 mm deficit irrigation under the ridge furrow system was appropriate due to increase ICWP and IWP. The plastic-covered ridge and furrow rainwater harvesting (RFRH) system has been used widely to enhance crop productivity in the semiarid regions of China. We conducted a field study during 2015–2017 where the RFRH method was combined with deficit irrigation to decrease the irrigation water usage and improve the crop water productivity (CWP) and irrigation water productivity (IWP). Under the RFRH system, the amount of irrigation was reduced by half compared with that under traditional flat planting (TF) with border irrigation due to the effects of precipitation harvesting. Half of the deficit irrigation was supplied before wintering and the remaining half at the jointing stage. The following eight treatments were tested: RFRH system with 75 mm deficit irrigation (R 75), 37 mm irrigation (R 37), 18 mm irrigation (R 18), and 0 mm irrigation (R 0); TF cultivation with 150 mm irrigation (F 150), 75 mm irrigation (F 75), 37 mm irrigation (F 37), and 0 mm irrigation (F 0). The results showed that the irrigation volume doubled under conventional border irrigation but the soil water storage was greater under RFRH with deficit irrigation. The R 75 treatment resulted in significantly greater soil water storage, reduced evapotranspiration (44.2%), and a higher grain yield (14.6%), thereby increasing CWP (64.8%), ICWP (irrigation crop water productivity) (44.2%), and IWP (57.0%) compared with F 150. R 75 improved the biomass per plant, leaf area index, and net income for farmers (by 17.5%) compared with F 150. Thus, we recommend R 75 for decreasing the irrigation water usage and increasing the effective consumption of precipitation in semiarid regions. [ABSTRACT FROM AUTHOR]

Monoculture is widely practiced to increase crop productivity, but long-term adaptation has drawbacks as it increases the depletion of soil nutrients and reduces soil quality, especially in dryland areas. Conversion from traditional maize monoculture to intercropping improves sustainable production. However, maize/peanut intercropping, especially rotation of planting strips impacts of maize/peanut intercropping in dryland on carbon (C) budgets and economic benefits remain unclear. In this study, a 5-year field experiment was conducted to evaluate the influence of maize/peanut intercropping with rotation of planting strips on soil health, indirect CO 2 -eq greenhouse gas emissions, and ecosystem C inputs. Four intercropping treatments viz. maize monoculture, peanut monoculture, maize/peanut intercropping, and maize/peanut rotation-intercropping were tested from 2018 to 2022. Maize/peanut rotation intercropping significantly improved the land equivalent ratio followed by intercropping and monoculture. Rotation-intercropping also improved economic benefits over intercropping and monoculture which were mainly associated with increased peanut yield where the border rows contributed the maximum, followed by the middle rows. Moreover, rotation-intercropping significantly increased the soil organic C and nitrogen (N) content. Rotation-intercropping decreased indirect CO 2 -eq greenhouse gas emissions and ecosystem C inputs by 3.11% and 18.04%, whereas increased ecosystem C outputs and net ecosystem C budget by 10.38% and 29.14%, respectively, over the average of monoculture. On average for intercropping and monoculture, rotation-intercropping increased ecosystem C emission efficiency for economic benefits by 51.94% and 227.27% in 2021 and 2022, respectively, showing the highest C utilization efficiency than other treatments. In the long run, maize/peanut rotation-intercropping can be practiced in dryland agriculture to achieve sustainable agriculture goals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

In semiarid regions, deficit and unpredictable precipitation results in yield losses. Uniconazole is a plant growth regulator and its application is beneficial in water saving agriculture and improves maize production in semiarid regions. In order to determine the effects of uniconazole application on seed filling and hormonal changes of maize, a field study was conducted in the summer of 2015 and 2016. Seeds were soaked in uniconazole at concentration of 0 (SCK), 25 (S 25 ), 50 (S 50 ), and 75 (S 75 ) mg kg -1 , while in the second experiment, uniconazole was applied to the foliage at concentration of 0 (FCK), 25 (F 25 ), 50 (F 50 ), and 75 (F 75 ) mg L -1 at the eight-leaf. Uniconazole application significantly improves the seed filling rates by regulating the endogenous hormones contents. Uniconazole seed soaking treatments improved significantly the seed filling rate of superior, middle, and inferior seeds compared with foliar application treatments. Uniconazole improved significantly the zeatin (Z) + zeatin riboside (ZR) and abscisic acid (ABA) contents while reducing the gibberellic acid (GA) content in the seeds during the process of seed filling. The Z + ZR and ABA contents were significantly positively correlated while the GA content was negatively correlated with maximum seed weight, maximum seed filling rates, and mean seed filling rates. Treatments S 25 and F 25 significantly improved the above dry matter accumulation plant -1 , seed filling rates, ABA, Z + ZR contents, characters of ear, and grain yield while reduced the GA content. It is concluded from our results that the uniconazole application at concentration of 25 mg kg -1 as seed soaking or 25 mg L -1 foliar applied at the eight-leaf stage is beneficial to improve the seed filling rates and grain yield of maize in semiarid regions.

In northern China, large-spike wheat (Triticum aestivum L) is considered to have significant potential for increasing yields due to its greater single-plant productivity despite its lower percentage of effective tillers, and increasing the plant density is an effective means of achieving a higher grain yield. However, with increases in plant density, the amount of solar radiation intercepted by lower strata leaves is decreased and the rate of leaf senescence is accelerated. Row spacing can be manipulated to optimize the plant spatial distribution under high plant density, therefore improving light conditions within the canopy. Consequently, field experiments were conducted from 2010 to 2012 to investigate whether changes in row spacing under high plant density led to differences in canopy apparent photosynthesis (CAP), individual leaf photosynthesis and grain yield. Two different spike-type winter wheat cultivars, Jimai22 (a small-spike cultivar as a control cultivar) and Wennong6 (a large-spike cultivar), were grown at a constant plant density of 3,600,000 plants ha(-1) (a relatively higher plant density) over a wide range of row spacing as follows: 5-cm row spacing (R0), 15-cm row spacing (R1), 25-cm conventional row spacing (R2), and 35-cm row spacing (R3). The two-year investigations revealed that increased row spacing exhibited a significantly higher light transmission ratio (LT), which improved light conditions within the canopy; however, excessive light leakage losses in R2 and R3 treatments were not favorable to improved irradiation energy utilization efficiency. Aboveground biomass accumulation was influenced by row spacing. Two spike-type wheat accumulated greater biomass under 15-cm row spacing compared to other row spacing treatments, although a markedly improved photosynthetic rate (PN), effective quantum yield of photosystem II (ΦPSII) and maximal efficiency of photosystem II photochemistry (Fv/Fm) in the penultimate and third leaves were observed in R2 and R3 treatments. At the same time, a longer duration of CAP and green leaf area was maintained in R1 during grain filling. Compared with conventional row spacing, Wennong6 in R1 treatment obtained 21.0% and 19.1% higher grain yield in 2011 and 2012, respectively, while for Jimai22 it increased by 11.3% and 11.4%, respectively. A close association of yield with CAP and LAI at mid-grain filling was observed. In conclusion, for the tested growing conditions, decreasing the row spacing to an optimal distance (15 cm) maintained a longer duration of LAI and CAP during grain filling, made a better coordination of group and individual leaf photosynthesis, and accumulated higher aboveground biomass, leading to a greater grain yield. In addition, Wennong6 had a more rational canopy architecture than Jimai22 (improved LT and higher LAI) and CAP under 15-cm row spacing, leading to a higher grain yield, which indicated that the large-spike type cultivar has the potential to obtain higher yields by increasing plant density through optimum row spacing allocation (15 cm).

Taking two winter wheat cultivars Ji' nan 17 and Shannong 8355 as test materials, this paper measured the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and the malondialdehyde (MDA) and soluble protein contents in the functional leaves and sheaths of the tillers at different positions at stem elongation stage under low temperature stress, and then, the freezing resistance of the tillers was comprehensively evaluated by the methods of principal component analysis and cluster analysis. The results showed that under low temperature stress, the SOD, POD, and CAT activities in the functional leaves and sheaths of each tiller at stem elongation stage increased, but the MDA and soluble protein contents increased or decreased to some extent. By using principal component analysis and cluster analysis, the tillers of each cultivar were grouped into three kinds of freezing resistance type. For Ji' nan 17, the main stem, tiller I, and tiller II belonged to high freezing resistance type, the tiller III, tiller IV, and tiller I p belonged to medium freezing resistance type, and the tiller II p belonged to low freezing resistance type. For Shannong 8355, the main stem, tiller I, tiller II, and tiller III belonged to high freezing resistance type, the tiller IV and tiller I p belonged to medium freezing resistance type, and the tiller II p belonged to low freezing resistance type. It was concluded that the freezing resistance of the winter wheat tillers at different positions at stem elongation stage differed, with the lower position tillers being more resistant than the higher position tillers.