Optimization of fertilization scheme based on sustainable wheat productivity and minor nitrate residue in organic dry farming: An empirical study.

The substitution of chemical nitrogen fertilizer with manure holds the potential for a synergistic rise in wheat grain yield and protein concentration, while minimizing residual nitrate in soil. We conducted a 6-year field fertilization experiment including two manure treatments (with or without) and five nitrogen applications rates (0, 60, 120, 180 and 240 kg ha-1). The study investigated the impact of single chemical nitrogen (CN) and manure substitution for nitrogen fertilizer (MN) on the grain yield (GY), grain protein concentration (GPC), plant nitrogen uptake (PNupt) and plant nitrogen requirement (PNR) of wheat, and the dynamic change of soil nitrate-N. The findings revealed that: (1) the MN demonstrated a greater advantage over CN, as evidenced by a 13.4-16.0 % increase in GY, a 2.6-3.8 % increase in GPC, a 7.2-15.7 % increase in PNupt and a 1.5-4.7 % reduction in PNR. (2) Soil nitrate accumulation (SNA) significantly increased when fertilizer rates ≥180 kg ha-1 and the peak annually shifted to deeper layer. The MN increased the SNA0-100 by 20.9-21.8 %, but significantly reduced SNA0-200 by 11.8-13.5 % compared with the CN. Topsoil nitrate content (SNC0-20) can be adopted as a substitute for SNA0-100 to make the fertilization schedule convenient. (3) Regression analysis revealed (taking the MN for example) that the optimum N rates for the maximum GY (5417 kg ha-1) and GPC (15.3 %) were 164 and 211 kg N ha-1, respectively. The nitrate-N safety threshold was 62 kg ha-1 at the fertilizer rate of 89 kg N ha-1. Based on this, nitrogen fertilizer input reduced by 44.8-57.2 % and SNA0-200 by 17.9-33.6 %, with achieving 91.8-95.0 % of maximum GY and 89.7-92.9 % of maximum GPC. Substituting manure for nitrogen fertilizer achieved the potential of maintaining the grain yield and protein concentration while the minimization in soil nitrate residue. This study offers a feasible way for fertilization recommendation and nitrate residue controlling in dry farming.

Effects of elevated atmospheric ammonia concentration on photosynthetic characteristics and grain yield in wheat under different nitrogen rates.

To evaluate the effects of nitrogen (N) application rates on the growth, photosynthetic traits and yield of winter wheat under elevated atmospheric ammonia (NH3) concentrations could provide guidance for N management under high NH3 environment. We conducted a split-plot experiment for two consecutive years (2020-2021 and 2021-2022) with top-open chambers. The treatments included two NH3 concentrations [elevated ambient NH3 concentration at 0.30-0.60 mg·m-3 (EAM) and air NH3 concentration at 0.01-0.03 mg·m-3 (AM)] and two N application rates [recommended N dose (+N) and no N application (-N)]. We analyzed the effects of aforementioned treatments on net photosynthetic rate (Pn), stomatal conductance (gs), chlorophyll content (SPAD value), plant height, and grain yield. The results showed that averaged across the two years, EAM significantly increased Pn, gs, and SPAD values at the jointing and booting stages at the -N level by 24.6%, 16.3%, 21.9% and 20.9%, 37.1%, 5.7%, respectively, compared with AM. However, EAM significantly decreased Pn, gs, and SPAD values at jointing and booting stages at +N level by 10.8%, 5.9%, 3.6% and 6.8%, 18.9%, 9.3%, respectively, over AM treatment. There was a significant effect of NH3 treatment, N application rates and their interaction on plant height and grain yield. Compared with AM, EAM increased the average plant height and grain yield by 4.5% and 32.1% at -N level and decreased by 1.1% and 8.5% at +N level, respectively. In a nutshell, the eleva-ted ambient NH3 concentration had positive effect on photosynthetic characteristics, plant height, and grain yield under ambient N condition, but a inhibitory effect under N application.

Adaptive nitrogen inputs sustain water-nitrogen use and improve maize productivity with varied precipitation conditions on a semi-arid agroecosystem.

BACKGROUND: Maize productivity in semi-arid regions is increasingly at risk because of the sparse and uneven precipitation, and it is also restricted by excessive or insufficient fertilization management strategies. A 4-year (2016-2019) field experiment was therefore conducted to show the effects of fertilizer with five nitrogen levels (0, 75-90, 150-180, 270, and 360 kg ha-1 , represented as N0 , N75-90 , N150-180 , N270 , N360 , respectively) under two variable precipitation patterns (rainy at pre-anthesis in 2016 and 2018 versus dry at pre-anthesis in 2017 and 2019) on soil water storage (SWS), water use efficiency (WUE), nitrogen use efficiency (NUE), and maize yield in the Loess Plateau. RESULTS: Nitrogen inputs increased the amount of above-ground dry matter and the WUE for dry matter (WUEd). Dry years at pre-anthesis significantly reduced dry matter accumulation and kernel number per plant. However, soil water storage before sowing (SWSs) decreased from 440 mm in 2016 to 384 mm in 2019, and the increase in fertilization resulted in the water imbalance. Both the maximum grain yield and WUE for grain yield were found in N270 under rainy years at pre-anthesis, whereas in N150-180  under dry years at pre-anthesis. The average nitrogen recovery efficiency (NRE), nitrogen agronomy efficiency (NAE) and nitrogen partial factor productivity (NPFP) decreased with increases in N application, compared with N360 , the NRE,NAE and NPFP of N150-180 increased by 63.5%, 189.2% and 135.5%, respectively. CONCLUSIONS: Reducing basal N fertilizers could enhance maize yield and maintain moderate water and nitrogen productivity in years with less rainfall. © 2023 Society of Chemical Industry.

Ridge cropping and furrow irrigation pattern improved spring maize (Zea mays L.) yield and water productivity in Hetao irrigation area of north-western China.

BACKGROUND: Improving irrigation water productivity is vital for sustaining high maize yield in Hetao irrigated area of northwest China. Whether ridge cropping and furrow irrigation systems (planting both on ridges and in furrows) fulfill water-saving and maize yield-increasing is unclear. A 2-year trial was conducted to reveal the influence of irrigation with three levels (270, 225, 180 mm, represented as I270 , I225 , I180 , respectively) under two planting systems [traditional flat planting system (TFI) and ridge cropping and furrow irrigation system (RFI)] on maize growth, grain yield, water use efficiency (WUE) and irrigation water use efficiency (IUE). RESULTS: RFI system increased soil water storage in 0-100 cm layer (P < 0.05), but did not cause excess water consumption, compared to TFI system. Logistic equation simulation showed that RFI system advanced the time of maximum dry matter growth rate (Tmax , 2.6-4.9 days) and prolonged the duration of dry matter accumulation (Td , 3.2-4.7 days), ultimately obtained a 4.2-9.5% improvement of dry matter. Compared with TFI system, RFI system increased WUE by 8.0-21.2%, IUE by 8.3-20.5% and grain yield increased by 9.4-21.4%. RFI225 satisfied water-saving by 16.6% and yield-increasing by 3.6-14.7%. CONCLUSION: Ridge cropping and furrow irrigation systems brought an improvement of soil water storage and dry matter accumulation and kernel per spike, and ultimately obtained an increase of grain yield and water productivity. © 2022 Society of Chemical Industry.

[Effects of water limiting and nitrogen reduction on nitrogen use and apparent balance of winter wheat in the Guanzhong Plain, Northwest China]. / é™æ°´å‡æ°®å¯¹å ³ä¸­å¹³åŽŸå†¬å°éº¦æ°®ç´ åˆ©ç”¨å’Œæ°®ç´ è¡¨è§‚å¹³è¡¡çš„å½±å“.

Effects of water limiting and nitrogen reduction on yield, nitrogen use efficiency and nitrogen apparent balance of wheat were investigated to explore whether it would be feasible to restrict water and reduce nitrogen in wheat production of the Guanzhong Plain and thus to provide scientific supports for yield-stable, high-efficiency, and environment-friendly developments in the irrigated production of winter wheat. Following a split-plot design with two water regimes as the main plots and four N addition rates as sub-plot factors, a field experiment (2017-2019) was conducted in Yangling, Shaanxi. The two water regimes were conventionally irrigating at the rate of 60 mm during the overwinter period and at the jointing stage, respectively (W2, a conventional practice) and irrigating at a rate of 60 mm during the overwintering period (W1, a restrictive irrigation practice). The four nitrogen addition rates were 300 kg·hm-2(N300, a conventional N rate), 225 kg·hm-2 (N225, a nitrogen rate of 25% less than the convention), 150 kg·hm-2(N150, a nitrogen rate 50% of less than the convention), and 0 kg·hm-2(N0, no nitrogen applied). The decreased irrigation rate and nitrogen rate significantly increased nitrogen content in the plants and grains, yield, N output, nitrogen use efficiency, nitrogen harvest index, nitrogen recovery efficiency, and nitrogen agronomic efficiency, reduced nitrate leaching and N surpluses, and maintained nitrogen balance. With both W1 and N150 adopted, the increased irrigation rate and nitrogen rate did not affect yield and N output of winter wheat in 2017-2019. Plant nitrogen content with both W1 and N150 adopted increased by 0.1%-25.5% and 14.0%-31.6% and the grain nitrogen content increased by 0.1% and 4.6%, compared with those with both W2 and N300 adopted in 2017-2018 and 2018-2019, respectively. Nitrogen use efficiency, nitrogen harvest index, nitrogen recovery efficiency, and nitrogen agronomic efficiency were averagely increased by 95.3%, 4.2%, 81.7% and 33.0% respectively. The N surplus was decreased by 97.2% and 95.1%, which effectively alleviated soil nitrate leaching. Considering all the indicators, irrigating at 600 m3·hm-2 during the overwintering period plus applying nitrogen at 150 kg·hm-2 could achieve high yield, high efficiency, and environment friendly development of winter wheat in the Guanzhong Plain of Shaanxi.

[Effects of reduced nitrogen application on yield, nitrogen utilization of spring maize and soil nitrate content in Weibei dryland, Northwest China]. / å‡é‡æ–½æ°®å¯¹æ¸­åŒ—æ—±åœ°æ˜¥çŽ‰ç±³äº§é‡ã€æ°®ç´ åˆ©ç”¨åŠåœŸå£¤ç¡æ€æ°®å«é‡çš„å½±å“.

To get a scientific pattern for nitrogen-reducing and efficiency-increasing production of spring maize in Weibei dryland, we conducted an in-situ field experiment of spring maize (Zhengdan 958 and Shaandan 8806) under dryland farming from 2016 to 2019 in Heyang County, located in Weibei dryland of Shaanxi. There were five nitrogen (N) treatments, including 360 kg·hm-2(N360, a rate commonly adopted by local farm households), 270 kg·hm-2(N270), 150-180 kg·hm-2(N150-180), 75-90 kg·hm-2(N75-90) and 0 kg·hm-2(N0). We investigated the effects of reduced nitrogen application on maize yield, nitrogen uptake and utilization of spring maize and soil nitrate residue. The results showed that: 1) Maize yield of both varieties at N150-180 was increased by 0.9%-7.1% and nitrogen uptake was decreased by 4.1%-4.6%, while average reco-very efficiency, partial-factor productivity and agronomic efficiency of N at N150-180 were increased by 79.3%-83.6%, 105.9%-157.7%, and 101.9%-114.1% compared with those at N360, respectively. 2) The contents of residual nitrate increased significantly when nitrogen application rate was more than 180 kg·hm-2, while nitrogen uptake was significantly reduced under rainfall shortage, and thus resulted in increasing soil residual nitrogen. After four-year treatments, the residual nitrate was up to 504.7-620.8 kg·hm-2 in 0-200 cm soil layer, with a peak in 80-140 cm soil layer. There was a risk of nitrate leaching. According to the comprehensive evaluation for annual yield, nitrogen use efficiency and soil nitrate residue, the optimum N application rate was recommended to be 150-180 kg N·hm-2 for spring maize in Weibei dryland.