Improving the water-use efficiency (WUE) of crops is the most effective way to increase yields in semi-arid regions. Field research was carried out based on a long-term experiment initiated in 2001, aimed to explore the mechanisms of different tillage practices effects on grain yield and WUE of spring wheat. Tillage practices in the research including conventional tillage (CT), no tillage with no straw mulching (NT), conventional tillage with straw incorporation (TS), and no tillage with straw mulching (NTS). The effects of tillage practices on soil’s physical and chemical properties, dry matter accumulation, grain yield, dynamics of stress-related substances, and WUE were observed. Soil and plant samples in this research were collected in 2020 (wet year), 2021 (dry year), and 2022 (dry year). The results indicated that NTS improved the soil’s physical and chemical properties. The NTS treatment had the lowest soil bulk and pH and the highest total N, NO3--N, and available P. Throughout the whole growth stage, soil water content in the NTS and TS treatments were significantly higher than that of CT by 8.77–20.40% and 2.19–18.83, respectively. Averaged catalase (CAT), peroxidase (POD), and soluble protein across the three years with NTS and TS were significantly increased by 1.26–25.52% compared to CT. Meanwhile, the NTS treatment had the lowest malondialdehyde (MDA) content among the different tillage practices. NTS maintained the highest dry matter accumulation throughout the whole growth stage among different treatments; it was increased by 10.47–73.33% compared with CT. The average grain yields and WUE of NTS across the three years were 6.09–30.70% and 6.79–40.55% higher than other tillage practices, respectively. It is concluded that NTS influences dry matter accumulation and water-use efficiency during the whole growth stage of spring wheat by improving the soil’s physicochemical properties and modulating spring wheat substances related to stress, which in turn promotes yield formation.
The application of organic fertilizers has become an increasingly popular substitution in maize production to reduce gaseous nitrogen (N) loss and soil degradation caused by inorganic fertilizers. Organic fertilizer plays a key role in improving soil quality and stabilizing maize yields, but studies that refine different substitution rates remain poorly documented. A field study was carried out in 2021 and 2022 based on a long-term trial initiated in 2016. The experiment included five organic fertilizer N substitution rates with equal input of 200 kg N ha–1: 0% organic fertilizer (T1, 100% inorganic fertilizer), 50.0% organic+50.0% inorganic fertilizer (T2), 37.5% organic+62.5% inorganic fertilizer (T3), 25.0% organic+75.0% inorganic fertilizer (T4), 12.5% organic+87.5% inorganic fertilizer (T5), and no fertilizer control (T6). The average result of two years showed that T3 and T1 had the highest grain yield and biomass, respectively, and there was no significant difference between T1 and T3. Compared with T1, 12.5, 25.0, 37.5, and 50.0% substitution rates (T5, T4, T3, and T2) significantly reduced total nitrogen loss (NH3、N2O) by 8.3, 16.1, 18.7, and 27.0%, respectively. Nitrogen use efficiency (NUE) was higher in T5, T3, and T1, and there was no significant difference among them. The organic fertilizer substitution directly reduced NH3 volatilization and N2O emission from farmland by lowering ammonium nitrogen and alkali-dissolved N content and by increasing soil moisture. These substitution treatments reduced N2O emissions indirectly by regulating the abundance of AOB and nirK-harboring genes by promoting soil moisture. The 37.5% of organic fertilizer substitution reduces NH3 volatilization and N2O emission from farmland by decreasing ammonium nitrogen and alkali-dissolved N content and increasing moisture which negatively regulate the abundance of AOB and nirK-harboring genes to reduce N2O emissions indirectly in rainfed maize fields on the Loess Plateau of China.
Introduction An appropriate supply of ammonium (NH4+) in addition to nitrate (NO3−) can greatly improve plant growth and promote maize productivity. However, knowledge gaps exist regarding the mechanisms by which different nitrogen (N) fertilizer sources affect the enzymatic activity of nitrogen metabolism and non-structural carbohydrates during the post-anthesis period. Methods A field experiment across 3-year was carried out to explore the effects of four nitrateammonium ratio (NO3−/NH4+ = 1:0 (N1), 1:1 (N2), 1:3 (N3), and 3:1 (N4)) on postanthesis dry matter (DM) and N accumulation, partitioning, transportation, and grain yield in maize. Results NO3-/NH4+ ratio with 3:1 improved the enzymatic activity of N metabolism and non-structural carbohydrate accumulation, which strongly promoted the transfer of DM and N in vegetative organs to reproductive organs and improved the pre-anthesis DM and nitrogen translocation efficiency. The enzymatic activities of nitrate reductase, nitrite reductase, glutamine synthetase, glutamine oxoglutarate aminotransferase, and non-structural carbohydrate accumulation under N4 treatment were increased by 9.30%–32.82%, 13.19%–37.94%, 4.11%–16.00%, 11.19%–30.82%, and 14.89%–31.71% compared with the other treatments. Mixed NO3−-N and NH4+-N increased the total DM accumulation at the anthesis and maturity stages, simultaneously decreasing the DM partitioning of stem, increasing total DM, DM translocation efficiency (DMtE), and contribution of pre-anthesis assimilates to the grain (CAPG) in 2015 and 2017, promoting the transfer of DM from stem to grain. Furthermore, the grain yield increased by 3.31%–9.94% (2015), 68.6%–26.30% (2016), and 8.292%–36.08% (2017) under the N4 treatment compared to the N1, N2, and N3 treatments. Conclusion The study showed that a NO3−/NH4+ ratio of 3:1 is recommended for high-yield and sustainable maize management strategies in Northwestern China.
Wheat grain yield and nitrogen (N) content are influenced by the amount of N remobilized to the grain, together with pre-anthesis and post-anthesis N uptake. Isotopic techniques in farmed areas may provide insight into the mechanism underlying the N cycle. 15N-labeled urea was applied to microplots within five different fertilized treatments 0 kg ha-1 (N1), 52.5 kg ha-1 (N2), 105 kg ha-1 (N3), 157.5 kg ha-1 (N4), and 210 kg ha-1 (N5) of a long-term field trial (2003-2021) in a rainfed wheat field in the semi-arid loess Plateau, China, to determine post-anthesis N uptake and remobilization into the grain, as well as the variability of 15N enrichment in aboveground parts. Total N uptake was between 7.88 and 29.27 kg ha-1 for straw and 41.85 and 95.27 kg ha-1 for grain. In comparison to N1, N fertilization increased straw and grain N uptake by 73.1 and 56.1%, respectively. Nitrogen use efficiency (NUE) and harvest index were altered by N application rates. The average NUE at maturity was 19.9% in 2020 and 20.01% in 2021; however, it was usually higher under the control and low N conditions. The amount of 15N excess increased as the N rate increased: N5 had the highest 15N excess at the maturity stage in the upper (2.28 ± 0.36%), the middle (1.77 ± 0.28%), and the lower portion (1.68 ± 1.01%). Compared to N1, N fertilization (N2-N5) increased 15N excess in the various shoot portions by 50, 38, and 35% at maturity for upper, middle, and lower portions, respectively. At maturity, the 15N excess remobilized to the grain under N1-N5 was between 5 and 8%. Our findings revealed that N had a significant impact on yield and N isotope discrimination in spring wheat that these two parameters can interact, and that future research on the relationship between yield and N isotope discrimination in spring wheat should take these factors into account.
Although plastic film mulching is commonly utilized to enhance crop water use efficiency (WUE) in semi-arid areas, the combined effect of plastic film mulching and fertilizer application on Tartary buckwheat yield is still unknown. To address this gap, a four-year field experiment was conducted from 2018 to 2021 to investigate the effect of plastic film mulching and fertilizers on the soil water storage, plant growth, yield, and WUE of Tartary buckwheat in semi-arid environments. The treatments comprised traditional planting without fertilizer (TNF), traditional planting with fertilizer application (N–P2O5–K2O: 40–30–20 kg ha−1) (TF), plastic film mulching with fertilizer application (N–P2O5–K2O: 40–30–20 kg ha−1) (MF), and plastic film mulching without fertilizer (MNF). The results indicated that MF treatment significantly increased leaf area index and SPAD values compared to the other treatments. The yield of Tartary buckwheat under the film mulching increased by 23.3% in comparison to no-mulching treatments, and under fertilizer application it increased by 18.2% compared to no fertilizer. WUE under film mulching exhibited an increase of 3.1% in 2018, 34.9% in 2019, 45.5% in 2020, and 34.6% in 2021, respectively, compared to no mulching. The impact of film mulching on WUE was more significant in years with lower precipitation compared to those with normal or higher precipitation levels. Overall, MF significantly enhanced both the yield and WUE of Tartary buckwheat. This approach proved to be an effective strategy for bolstering drought-resistant yield and optimizing resource efficiency in Tartary buckwheat cultivation in semi-arid regions. Moreover, the positive effects of plastic mulching and fertilizer application on grain yield and water use efficiency were more pronounced in drier years.
Increasing agricultural productivity without undermining further the integrity of the Earth’s environmental systems such as soil water balance are important tasks to ensure food security for an increasing global population in rainfed agriculture. The impact of intercropping maize (Zea mays L.) with potato (Solanum tuberosum L.) on yield, land equivalent ratios (LER), water equivalent ratio (WER), water use, energy output, and net economic return were examined under seven planting systems: potato grown solely or intercropped on the flat field without mulching, maize grown solely or intercropped with potato on ridges or flat field with or without plastic film mulched. The three intercropping systems had 3–13% less water use than the monocropping. Among the intercropped systems, flat field caused more depletion of soil water than ridged field for both years. Compared to monocultures, intercropping with plastic film mulching and ridging significantly increased LER and WER. Meanwhile, intercropping with mulching and ridging significantly increased net economic return and energy output by 8% and 24%, respectively, when compared to monocropping. These results suggest that maize under plastic film mulched ridge-furrow plot intercropped with potato under flat plot without mulching increased energy output, net economic return, and water use efficiency without increasing soil water depletion, which could be an optimal intercropping system for the semiarid farmland on the western Loess Plateau.
To investigate the effects and mechanism of prolonged inorganic nitrogen (N) fertilization on the N-use efficiency of spring wheat (Triticum aestivum L.), a long-term study initiated in 2003 was conducted. The study analyzed how N fertilization affects dry matter translocation, N translocation, soil NO3-N, and N-use efficiency. Five different N-fertilizer rate treatments were tested: N0, N52.5, N105, N157.5, and N210, corresponding to annual N fertilizer doses of 0, 52.5, 105.0, 157.5, and 210.0 kg N ha−1, respectively. Results showed that increasing N-fertilizer rates significantly enhanced the two-year average dry matter accumulation amount (DMA) at maturity by 22.97–56.25% and pre-flowering crop growth rate (CGR) by 17.11–92.85%, with no significant increase beyond 105 kg N ha−1. However, no significant correlation was observed between the dry matter translocation efficiency (DTE) and wheat grain yield. Both insufficient and excessive N applications resulted in an imbalanced N distribution favoring vegetative growth over reproductive growth, thus negatively impacting N-use efficiency. At maturity, the N-fertilized treatments significantly increased the two-year average N accumulation amount (NAA) by 52.04–129.98%, with no further increase beyond 105 kg N ha−1. N fertilization also improved the two-year average N translocation efficiency (NTE) by 56.89–63.80% and the N contribution proportion (NCP) of wheat vegetative organs by 27.79–57.83%, peaking in the lower-N treatment (N52.5). However, high-N treatment (N210) led to an increase in NO3-N accumulation in the 0–100 cm soil layer, with an increase of 26.27% in 2018 and 122.44% in 2019. This higher soil NO3-N accumulation in the 0–100 cm layer decreased NHI, NUE, NAE, NPFP, and NMB. Additionally, N fertilization significantly reduced the two-year average N harvest index (NHI) by 9.89–12.85% and N utilization efficiency (NUE) by 11.14–20.79%, both decreasing with higher N application rates. The NAA followed the trend of anthesis > maturity > jointing. At the 105 kg N ha−1 rate, the highest N agronomic efficiency (NAE) (9.31 kg kg−1), N recovery efficiency (NRE) (38.32%), and N marginal benefit (NMB) (10.67 kg kg−1) were observed. Higher dry matter translocation amount (DTA) and N translocation amount (NTA) reduced NHI and NUE, whereas higher NTE improved NHI, NUE, and N partial factor productivity (NPFP). Overall, N fertilization enhanced N-use efficiency in spring wheat by improving N translocation rather than dry matter translocation.
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