This study investigates the effects of wheat straw incorporation and subsurface pipe depth on water-salt transport in coastal saline soil, providing technical references for saline-alkali land improvement. A soil column infiltration experiment with a straw interlayer was conducted, comparing four straw incorporation treatments-S0 (0 t & centerdot;ha-1), S1 (5 t & centerdot;ha-1), S2 (10 t & centerdot;ha-1) and S3 (15 t & centerdot;ha-1)-under two subsurface pipe depths: H1 (0.8 m) and H2 (0.6 m). The results indicate that the straw layer affects water infiltration, initially inhibiting water infiltration during the early stage but promoting infiltration and enhancing the leaching efficiency of surface salts during the stable stage. The leaching effectiveness follows the order S3 -> S2 -> S1 -> S0. Under the same straw incorporation rate, the drainage electrical conductivity of the H1 treatment is 154% higher than that of H2, suggesting that deeper drainage systems are more conducive to salt leaching. Considering technical effectiveness and practical feasibility, a synergistic regulation scheme is recommended: straw incorporation at 10 t & centerdot;ha-1 (S2 level) combined with a subsurface pipe burial depth of 0.8 m (H1 level). This approach achieves the improvement goals of enhanced infiltration and efficient salt drainage. Cette & eacute;tude examine les effets exerc & eacute;s par l'incorporation de paille de bl & eacute; et la profondeur des tuyaux souterrains sur le transport de l'eau et du sel dans les sols salins c & ocirc;tiers, fournissant ainsi des r & eacute;f & eacute;rences techniques pour l'am & eacute;lioration des terres salines et alcalines. Une exp & eacute;rience d'infiltration en colonne de sol int & eacute;grant une couche interm & eacute;diaire de paille a & eacute;t & eacute; men & eacute;e, par rapport & agrave; quatre traitements d'incorporation de paille-S0 (0 t & centerdot;ha-1), S1 (5 t & centerdot;ha-1), S2 (10 t & centerdot;ha-1) et S3 (15 t & centerdot;ha-1)-& agrave; deux profondeurs de tuyaux souterrains: H1 (0,8 m) et H2 (0,6 m). Les r & eacute;sultats montre que la couche de paille affecte l'infiltration de l'eau, en l'inhibant initialement au d & eacute;but de l'exp & eacute;rience, mais en la favorisant et en am & eacute;liorant l'efficacit & eacute; du lessivage des sels de surface pendant la phase stable. L'efficacit & eacute; du lessivage suit l'ordre S3 -> S2 -> S1 -> S0. & Agrave; taux d'incorporation de paille & eacute;gal, la conductivit & eacute; & eacute;lectrique du drainage dans le cadre du traitement H1 est sup & eacute;rieure de 154% & agrave; celle du traitement H2, indiquant que les syst & egrave;mes de drainage plus profonds sont plus favorable au lessivage des sels. Compte tenu de l'efficacit & eacute; technique et de la faisabilit & eacute; pratique, un sch & eacute;ma de r & eacute;gulation synergique est recommand & eacute;: l'incorporation de paille & agrave; raison de 10 t & centerdot;ha-1 (niveau S2) combin & eacute;e & agrave; une profondeur d'enfouissement des tuyaux souterrains de 0,8 m (niveau H1). Cette approche permet d'atteindre les objectifs d'am & eacute;lioration d'une infiltration renforc & eacute;e et d'un drainage efficace des sels.

To address the issue of freshwater scarcity for agricultural irrigation in arid and semi-arid regions, saline water and reclaimed water have great potential as alternative irrigation water. Therefore, a three-year field study was conducted in the Yinbei Irrigation District of Ningxia, China, to investigate the effects of alternate drip irrigation using freshwater (F), saline water (S) and reclaimed water (R) on sunflower growth. The study established six alternate drip irrigation schedules (SSR, SRS, RSS, SRR, RSR, RRS) and three continuous drip irrigation modes (FFF, SSS, RRR) based on the key sunflower growth stages: emergence-budding, budding-flowering, and flowering-maturity. The results revealed that during the emergence-budding stage and budding-flowering stage, saline water irrigation favored the allocation of dry matter to the roots, whereas reclaimed water irrigation was more effective in allocating dry matter to the leaves and faceplate, and significantly promoted nitrogen and phosphorus accumulation in sunflower plants. Furthermore, reclaimed water irrigation dramatically increased the crude protein content (12.6 %-15.4 %), unsaturated fatty acid content, and saturated fatty acid content in sunflower grains. During the flowering-maturity stage, reclaimed water irrigation was more conducive to dry matter accumulation in the plant, biomass allocation to the faceplate and grains, and resulted in an increase in sunflower grain yield by 2.1 %-5.0 %. Additionally, reclaimed water irrigation during the flowering-maturity stage significantly promoted radial development of the sunflower faceplate and markedly increased the linoleic acid and palmitic acid contents in the kernels, compared to saline water irrigation. The optimal irrigation schedule for sunflower cultivation in arid and semi-arid agricultural areas of China was suggested to be alternate irrigation with saline water during the emergence-budding stage and reclaimed water during the budding-flowering stage and flowering-maturity stage.

Ningxia is one of the main tomato-planting regions in China, but unreasonable irrigation modes and excessive fertilization rates have restricted the efficient development of local agriculture. Field experiments were carried out during 2019-2020 in Yinbei Irrigation District of Ningxia, China, to investigate the coupling effects of different micro-nano aeration ratios and topdressing levels on tomato growth and development, with underground drip irrigation system. The aeration ratios consist of non-aeration (0), low aeration (5 %), medium aeration (10 %) and high aeration (15 %). The topdressing levels of urea-tricalcium superphosphate-potassium sulfate included high topdressing (180-400-480 kg center dot ha-1 , traditional level), medium topdressing (135-300-360 kg center dot ha-1 ) and low topdressing (90-200-240 kg center dot ha-1 ). Results indicated that increasing the aeration ratio stimulated root viability and the development of fine root (diameter in 0-2 mm) to moderate root (diameter in 2-5 mm); raised leaf net photosynthetic rate, single fruit weight and tomato yield; and promoted the accumulation of organic acid, vitamin C, soluble sugar and soluble protein in tomato fruits. With the same aeration ratio, decreasing the high topdressing level to medium topdressing level increased single fruit weight and tomato yield, accelerated fruit expansion, promoted soluble solids and soluble sugar accumulation. Besides, increasing the aeration ratio by 10 % or 15 % was enough to alleviate the adverse effects of decreasing the high topdressing level to medium topdressing level. Considering the decrease of topdressing fertilizer application amount, increasing tomato yield and improving fruit quality, the present study suggested that the appropriate topdressing level of urea-triple superphosphate-potassium sulfate and the corresponding proper aeration ratio for tomato underground drip irrigation in the Yinbei Irrigation District of Ningxia was 135-300-360 kg center dot ha-1 and 15 %, respectively. The obtained proper combination of micro-nano aeration ratio and topdressing level can provide a scientific basis for the management of aerated underground drip irrigation and fertilization in northeast Ningxia of China and other agricultural districts with similar environments.

[Objective]To explore the optimal salt composition and salt concentration of irrigation water suitable for tomato field cultivation in arid and semi-arid areas.[Methods]Three salinity levels(1,2,and 3 g/L)and five Na∶Ca molar concentration ratio levels(1,3,5,7,and 9)of irrigation water were used in a 3-year field experiment of drip irrigation under tomato film in Yinbei irrigation district of Ningxia,China.[Results]The experiment found that with lower irrigation water salinity(1 g/L),appropriate increases in the Na:Ca molar ratio of irrigation water were beneficial for the accumulation of tomato plant dry matter and nutrients.Tomato fruit weight,marketable yield,and total yield decreased linearly with the increase of irrigation water Na∶Ca molar ratios.Moreover,with each increase in Na:Ca molar ratio of irrigation water,the tomato marketable yield decreased by 5 761.7 to 6 036.7 kg/hm2.Irrigation water with"high salinity(2,3 g/L)and low Na:Ca molar ratio(1 and 3)"was more profitable for tomato yield increase than irrigation water with"low salinity and high Na:Ca molar ratio".The soil sodium adsorption ratio in 0-40 cm and the amount of soil salt accumulation in 0-100 cm increased linearly with the increase of irrigation water Na∶Ca molar ratio.[Conclusion]To alleviate the soil salt accumulation and obtain a relatively high fruit yield during the growth period of field cultivated tomatoes in Yinbei irrigation area of Ningxia,irrigation water with salinity of 2 g/L and Na∶Ca molar concentration ratio of 5 was recommended for mulched drip irrigation,under the control limit of soil matrix potential at-20 kPa.

[Objective]The study aimed to explore the effects of aeration on crop growth characteristics and soil environmental characteristics in the root zone under reduced topdressing conditions.[Methods]The present paper took the field cultivated tomato in Yinbei irrigation area of Ningxia as the research object.Four groups of micro-nano gas aeration ratios(0,5％,10％,and 15％)and three topdressing fertilizer(urea-triple superphosphate-potassium sulfate)levels(180-400-480 kg/hm2,135-300-360 kg/hm2,and 90-200-240 kg/hm2)were set up for the two-year field experiment conducted in 2019 and 2020.[Results]With the same topdressing level,the dry matter and nutritional elements(N,P,and K)accumulation in the plant increased with the increase of aeration ratio,and increasing the aeration ratio was beneficial to the accumulation of phosphorus in roots during flowering-fruit setting period and the potassium accumulation at fruit expansion stage.With the same topdressing level,the tomato yield increased by 14.0％～44.2％as the aeration ratio increased by 5％～15％.With the same aeration ratio,the tomato yield increased by 0.4％～9.1％as the topdressing level was appropriately reduced(-25％)compared with the traditional fertilization.The increase of the aeration ratio and topdressing level was beneficial to increase the soil enzymes(catalase,alkaline phosphatase,and urease)activity significantly during the flowering-fruit setting period and fruit enlargement period of tomato.With the same topdressing level,increasing the aeration ratio by 5％～15％corresponded to an increase in soil enzyme activity by 27.5％～122.9％.[Conclusion]It was suggested that,to promote tomato plant growth,stabilize tomato yield and improve the soil enzymes activity in the Yinbei irrigation district,the suitable topdressing level of"urea-triple superphosphate-potassium"was 135-300-360 kg/hm2(25％lower than the traditional topdressing amount),and the suitable micro-nano aeration ratio was 10％.

Aiming at the problems of reduced winter wheat yield and aggravation of nitrogen leaching pollution caused by the waterlogging in the Middle-Lower Yangtze Plain, China, a two-year field experiment with three farmland water levels (W40, W60, W80) and three nitrogen application rates (N150, N225, N300) as well as a non-waterlogged treatment (CK) was carried out, to investigate the coupling effects of farmland water level and nitrogen application rate on the plant growth, grain yield, crop water productivity (WPC) and nitrogen load with waterlogging conditions. Three man-made waterlogging events were applied at winter wheat jointing-booting stage, heading-flowering stage and grain filling stage, respectively. The results indicated that with the farmland water level decreased from −40 cm to −60 cm and the nitrogen application rate increased from 150 kg∙ha−1 to 225 kg∙ha−1, the plant height, aboveground dry matter, leaf area index, spike length, grain yield, effective panicles, grain number per ear, 1000-grain weight and WPC in the waterlogging field increased significantly. However, since the nitrogen application rate exceeded 225 kg∙ha−1 and farmland water level lowered more than −60 cm, the favorable effects of nitrogen application rate and farmland water level for winter wheat growth and production reduced. Additionally, both the nitrogen load and partial factor productivity of nitrogen (PFPN) increased with the decline of farmland water level, while the nitrogen load increased and the PFPN decreased with the increasing nitrogen application rate. The raise of nitrogen rate from 150 kg∙ha−1 to 225 kg∙ha−1 was beneficial to plant growth, however, the increase of nitrogen application resulted in the decrease of PFPN and increase of drainage nitrogen loads. Compared with the water farmland water level of −40 cm and nitrogen application rate of 150 kg∙ha−1, the increase of nitrogen application rate and the decrease of farmland water level in the range of 50%-100% resulted in yield raise by 5.78%-32.29% approximately and the increase of nitrogen load by 36.20%-178.44% approximately. The comprehensive evaluation with TOPSIS-Entropy method for plant growth, grain yield, WPC, PFPN and nitrogen loads suggested that, the appropriate nitrogen application rate for winter wheat in the waterlogging areas of Middle-Lower Yangtze Plain in China was 225 kg∙ha−1, and the proper farmland water level was lowering to −80 cm in wet year and −60 cm in dry year within 3 days after waterlogging.

Introduction Unmanned aerial vehicles (UAVs) equipped with visible and multispectral cameras provide reliable and efficient methods for remote crop monitoring and above-ground biomass (AGB) estimation in rice fields. However, existing research predominantly focuses on AGB estimation based on canopy spectral features or by incorporating plant height (PH) as a parameter. Insufficient consideration has been given to the spatial structure and the phenological stages of rice in these studies. In this study, a novel method was introduced by fully considering the three-dimensional growth dynamics of rice, integrating both horizontal (canopy cover, CC) and vertical (PH) aspects of canopy development, and accounting for the growing days of rice.Methods To investigate the synergistic effects of combining spectral, spatial and temporal parameters, both small-scale plot experiments and large-scale field testing were conducted in Jiangsu Province, China from 2021 to 2022. Twenty vegetation indices (VIs) were used as spectral features, PH and CC as spatial parameters, and days after transplanting (DAT) as a temporal parameter. AGB estimation models were built with five regression methods (MSR, ENet, PLSR, RF and SVR), using the derived data from six feature combinations (VIs, PH+CC, PH+CC+DAT, VIs+PH +CC, VIs+DAT, VIs+PH+CC+DAT).Results The results showed a strong correlation between extracted and ground-measured PH (R2 = 0.89, RMSE=5.08 cm). Furthermore, VIs, PH and CC exhibit strong correlations with AGB during the mid-tillering to flowering stages. The optimal AGB estimation results during the mid-tillering to flowering stages on plot data were from the PLSR model with VIs and DAT as inputs (R 2 = 0.88, RMSE=1111kg/ha, NRMSE=9.76%), and with VIs, PH, CC, and DAT all as inputs (R 2 = 0.88, RMSE=1131 kg/ha, NRMSE=9.94%). For the field sampling data, the ENet model combined with different feature inputs had the best estimation results (%error=0.6%-13.5%), demonstrating excellent practical applicability.Discussion Model evaluation and feature importance ranking demonstrated that augmenting VIs with temporal and spatial parameters significantly enhanced the AGB estimation accuracy. In summary, the fusion of spectral and spatio-temporal features enhanced the actual physical significance of the AGB estimation models and showed great potential for accurate rice AGB estimation during the main phenological stages.

To explore the compensation effect of aeration on tomato vegetative and reproductive growth in arid and semi-arid areas, a two-year field experiment was conducted with four micro-nano aeration ratios (0%, 5%, 10%, and 15%) and three nitrogen topdressing levels (80, 60, and 40 kg·ha−1) during the tomato growth period in Ningxia, China. The results showed that increasing the aeration ratio in the range of 0–15% was conducive to the enhancement of tomato root vigor (the ability of triphenyltetrazolium chloride to be reduced, 3–104%) and the leaf net photosynthetic rate (14–63%), favorable to the facilitation of plant dry matter accumulation (3–59%) and plant nitrogen accumulation (2–70%), and beneficial to the improvement of tomato yield (12–44%) and fruit quality. Interestingly, since the aeration ratio exceeded 10%, the increase in the aeration ratio showed no significant effects on the single-fruit weight, tomato yield, and fruit quality. Moreover, with aerated underground drip irrigation, properly reducing the traditional nitrogen topdressing level (80 kg·ha−1) by 25% was favorable for enhancing tomato root vigor (5–31%), increasing tomato yield (0.5–9%), and improving fruit soluble solid accumulation (2–5%) and soluble sugar formation (4–9%). Importantly, increasing the aeration ratio by 5% could compensate for the adverse effects of reducing the nitrogen topdressing level by 25% by improving the leaf photosynthetic rate, promoting plant dry matter accumulation, increasing tomato yield, and enhancing the soluble solid and soluble sugar accumulation in tomato fruits. Synthetically considering the decrease in the nitrogen topdressing amount, leading to plant growth promotion, a tomato yield increase, and fruit quality improvement, a favorable nitrogen topdressing level of 60 kg·ha−1 and the corresponding proper aeration ratio of 10% were suggested for tomato underground drip irrigation in the Yinbei Irrigation District of Ningxia.

The sustainability of rice (Oryza sativa L.) cultivation has been threatened by water deficit and nitrogen (N)-fertilizer abuse. Straw return combined with N-fertilizer reduction could be an effective agronomic practice to improve N-use efficiency in rice production, but the interaction with water-saving irrigation regimes remains largely unknown. Here, a 2-year paddy field experiment was conducted to elucidate the effects of irrigation regime (continuously flooded, CF; controlled irrigation and drainage, CID) and straw return with N reduction (conventional farmers’ fertilization practice of 300 kg N ha−1 without straw return, N300; straw return with 25% N reduction, SN225; straw return with 50% N reduction, SN150) on rice growth dynamics, grain yield and water–nitrogen utilization. The results showed that CID significantly affected photosynthesis and fluorescence indicators, and increased grain yield and water productivity of rice. Straw return with N reduction reduced most rice growth traits, exhibiting lower plant height, tillers, leaf photosynthesis, chlorophyll fluorescence and dry matter accumulation, especially in vegetative growth under CF. In contrast, SN225 under CID showed compensatory effects on photosynthetic and fluorescence traits, thus improving N uptake during the reproductive growth stage. Despite a 6.6–7.1% yield reduction in SN225, 25% of N-fertilizer input was saved, with a corresponding increase in internal N-use efficiency and N-partial factor productivity. Overall, the present study indicates that straw return combined with moderate N deficiency might be a more eco-friendly and sustainable agronomic practice in water-saving irrigated rice fields.

To investigate the impact of brackish water irrigation on the multidimensional root distribution and root-shoot characteristics of summer maize under different salt-tolerance-training modes, a micro-plot experiment was conducted from June to October in 2022 at the experimental station in Hohai University, China. Freshwater irrigation was used as the control (CK), and different concentrations of brackish water (S0: 0.08 g·L−1, S1: 2.0 g·L−1, S2: 4.0 g·L−1, S3: 6.0 g·L−1) were irrigated at six-leaf stage, ten-leaf stage, and tasseling stage, constituting different salt tolerance training modes, referred to as S0-2-3, S0-3-3, S1-2-3, S1-3-3, S2-2-3, and S2-3-3. The results showed that although their fine root length density (FRLD) increased, the S0-2-3 and S0-3-3 treatments reduced the limit of root extension in the horizontal direction, causing the roots to be mainly distributed near the plants. This resulted in decreased leaf area and biomass accumulation, ultimately leading to significant yield reduction. Additionally, the S2-2-3 and S2-3-3 treatments stimulated the adaptive mechanism of maize roots, resulting in boosted fine root growth to increase the FRLD and develop into deeper soil layers. However, due to the prolonged exposure to a high level of salinity, their roots below 30 cm depth senesced prematurely, leading to an inhibition in shoot growth and also resulting in yield reduction of 10.99% and 11.75%, compared to CK, respectively. Furthermore, the S1-2-3 and S1-3-3 treatments produced more reasonable distributions of FRLD, which did not boost fine root growth but established fewer weak areas (FLRD < 0.66 cm−3) in their root systems. Moreover, the S1-2-3 treatment contributed to increasing leaf development and biomass accumulation, compared to CK, whereas it allowed for minimizing yield reduction. Therefore, our study proposed the S1-2-3 treatment as the recommended training mode for summer maize while utilizing brackish water resources.

Although unconventional water can be applied as an alternative for agricultural production, inappropriate irrigation water quality may adversely affect the soil crop system. Thus, field experiments under mulched drip irrigation were performed over three years (2017-2019) to investigate the impacts of three salinity (1, 2 and 3 g center dot L-1) with five Na:Ca molar ratios (1, 3, 5, 7 and 9) of irrigation water on tomato plant growth, fruit development, soil salt accumulation and soil sodium adsorption ratio. The results showed that, with irrigation water salinity of 1 g center dot L-1, the critical value of irrigation water Na:Ca molar ratio for the high yield and dry matter accumulation was 3 and 5, respectively, while the threshold for high concentration of vitamin C and lycopene was 7. With the irrigation water salinity of 2 g center dot L-1 and 3 g center dot L-1, the Na:Ca molar ratio threshold for a high concentration of soluble solids, vitamin C and lycopene was 5. Moreover, considering the increase of plant nitrogen and phosphorus accumulation, the decrease of sodium adsorption ratio at 40-100 cm soil layer inside the film, and the diminution of soil salt accumulation at 0-100 cm layer, irrigation water with higher salinity and lower Na:Ca molar ratio was more proper than that with lower salinity and higher Na:Ca molar ratio. Based on the multi-objective optimization with entropy-weight TOPSIS method, irrigation water with a salinity level at 2 g center dot L-1 and the Na:Ca molar ratio at 5 was suggested for tomato planting in the Yinbei Yellow River Irrigation District, China.

Rice production involves abundant water and fertilizer inputs and is prone to nitrogen (N) loss via surface runoff and leaching, resulting in agricultural diffuse pollution. Based on a two-season paddy field experiment in Jiangsu Province, China, field water and N dynamics and their balances were determined with the well-calibrated HYDRUS-1D model. Then, scenarios of different controlled drainage and N fertilizer applications were simulated using the HYDRUS-1D model to analyze the features and factors of N loss from paddy fields. Evapotranspiration and deep percolation were the two dominant losses of total water input over the two seasons, with an average loss of 50.9% and 38.8%, respectively. Additionally, gaseous loss of N from the whole soil column accounted for more than half of total N input on average, i.e., ammonia volatilization (17.5% on average for two seasons) and denitrification (39.7%), while the N uptake by rice accounted for 37.1% on average. The ratio of N loss via surface runoff to total N input exceeded 20% when the N fertilizer rate reached 300 kg ha−1. More and longer rainwater storage in rice fields under controlled drainage reduced surface runoff losses but increased the risk of groundwater contamination by N leaching. Therefore, compared with raising the maximum ponding rainwater depth for controlled drainage, optimizing N fertilizer inputs may be more beneficial for controlling agricultural diffuse pollution by reducing N loss via surface runoff and leaching. The HYDRUS-1D model provides an approach for the quantitative decision-making process of sustainable agricultural water and N management.

针对水域保护和利用过程中存在的诸多问题,根据平原区水域承载的功能,提出了从防洪除涝功能、抗旱供水功能和水环境容量3个方面确定适宜水面率的基本思路,建立了基于除涝抗旱与水生态要求的适宜水面率数学模型.以淮北平原区凌城灌区为例,计算了该区域的适宜水面率.结果表明,满足平原区除涝、抗旱与水生态要求的适宜水面率为10.52％.该方法可为类似平原灌区的水域监督检查、管理以及续建配套和现代化改造建设等提供参考.

Although saline water can be used as an alternative of freshwater resources for agricultural irrigation, especially in arid and semiarid areas, however, unsuitable saline water quality and unreasonable irrigation technology may result in the detrimental effects on plant growth, yield and quality of products. Thus, a three-year open field experiment was conducted in Ningxia to investigate the influence of three irrigation water salinity levels (1, 2 and 3 g/L) and five molar concentration ratios (MCR) of Na:Ca (1, 3, 5, 7 and 9) on processing tomato planting, in terms of crop water consumption, tomato yield traits and fruit quality characteristics. The results are as follow: (i) The water consumption decreased significantly with the increasing irrigation water salinity and MCR of Na: Ca. (ii) With the increase of irrigation water MCR of Na:Ca, both the average fruit weight, marketable yield and total yield decreased linearly, as well, the ratio of marketable yield to total yield decreased. Additionally, irrigation water with higher salinity (2 g/L and 3 g/L) and lower MCR of Na:Ca (1 and 3) was more conducive to root water uptake and average fruit weight accumulation, than that with lower salinity and higher MCR of Na:Ca. (iii) With irrigation water salinity of 1 g/L and 2 g/L, both the vitamin C, lycopene, fructose, sucrose and starch content of tomato fruit have quadratic function relationship with the irrigation water MCR of Na:Ca. Moreover, the threshold of irrigation water MCR of Na:Ca for soluble solids, lycopene and starch accumulation was 7, while the content of total soluble sugar, fructose and sucrose achieved the maximum value as the MCR of Na:Ca arrived 5. (iv) With irrigation water salinity of 3 g/L, the total soluble sugar and glucose of fruit decreased with the increase of irrigation water MCR of Na:Ca, especially, the fruit fructose, sucrose and starch concentration decreased linearly, furthermore, the threshold of irrigation water MCR of Na:Ca for vitamin C and soluble solids accumulation was 5. Synthetically, saline water with salt content of 2 g/L and MCR of Na:Ca at 5 was optimal in the present study for mulched drip irrigation on tomato cultivation in the northern Yinchuan plain of Ningxia, obtaining the relatively high-yield (9.72 x10(4) kg/hm(2)) and good-quality of tomato.

Understanding salinity and fertilizer interaction is of great importance to improve crop production and fertilizer use efficiency in saline areas. To evaluate the interactive effects of different soil salinity levels and nitrogen (N) applications rates on the sunflower photosynthetic characteristics of N uptake and N use efficiency, a two-year field experiment was conducted in Hetao Irrigation District, China. The experiment consisted of three initial salinity (IS) levels expressed as the electrical conductivity of a saturated soil extract (ECe) (S0: 1.72–2.61 dS/m; S1: 4.73–5.90 dS/m; S2: 6.85–9.04 dS/m) and four N rates (45, 90, 135, and 180 kg/ha), referred as N0–N3, respectively. The results indicated that the net photosynthetic rate (Pn) of sunflowers treated with S0 and S1 levels both had a significant decrease in the bud stage, and then reached their maximum at anthesis. However, during the crop cycle, the Pn at S2 level only had small fluctuations and still remained at a high level (>40 μmol CO2/(m2 s)) at the early mature stage. When increasing IS levels from S0 to S1, the plant N uptake (PNU) under the same N rates were only decreased by less than 10% at maturity, whereas the decline was expanded to 17.2–45.7% from S1 to S2. Additionally, though applying the N2 rate could not increase sunflower PNU at the S0 and S1 levels, its N use efficiency was better than those under N3. Meanwhile, at the S2 level, the application of the N0 rate produced a higher N productive efficiency (NPE) and N uptake efficiency (NUPE) than the other N rates. Therefore, our study proposed recommended rates of N fertilizer (S0 and S1: 135 kg/ha, S2: 45 kg/ha) for sunflowers under different saline conditions.

Effective water and nitrogen (N) management strategies are critical for sustainable agricultural development. Lysimeter experiments with two deep percolation rates (low percolation and high percolation, i.e., LP and HP: 3 mm d−1 and 5 mm d−1) and five N application levels (N0~N4: 0, 60, 135, 210 and 285 kg N ha−1) were conducted to investigate the effects of controlled drainage on water productivity (WP) and N use efficiency (NUE) in water-saving irrigated paddy fields. The results demonstrated that NH4+-N and NO3−-N were the major components of total nitrogen (TN) in ponded water and leachate, accounting for more than 77.1% and 83.6% of TN, respectively. The risk of N leaching loss increased significantly under treatment of high percolation rates or high N application levels. High percolation loss required greater irrigation input, thus reducing WP. In addition, N uptake increased with increasing N application, but fertilization applied in excess of crop demand had a negative effect on grain yield. NUE was affected by the amount of N applied and increased with decreasing N levels. Water and N application levels had a significant effect on N uptake of rice, but their interaction on N uptake or NUE was not significant. For the LP and HP regimes, the highest N uptake and WP were obtained with N application levels of 285 kg ha−1 and 210 kg ha−1, respectively. Our overall results suggested that the combination of controlled drainage and water-saving irrigation was a feasible mitigation strategy to reduce N losses through subdrainage percolation and to provide more nutrients available for rice to improve NUE, thus reducing diffuse agricultural pollution. Long-term field trials are necessary to validate the lysimeter results.

[目的]河西地区石羊河流域的农业生产中水资源短缺,光热资源利用率和水肥利用效率低.通过调整播期协调光热资源与水肥供应,研究提高春玉米生长及水肥利用效率的可能性.[方法]大田滴灌试验于2018年在甘肃省中国农业大学石羊河流域农业与生态节水试验站进行.设置3个播种日期,即4月10日(S1)、4月20日(S2)、4月30日(S3);2个灌水量水平,即80％ETc(I80)、100％ETc(I100)(ETc为作物蒸发蒸腾量);4个施氮量水平,即N 0、120、180、240 kg/hm2,分别表示为N0、N120、N180、N240.在玉米生长关键期,测定植株生长状况和水分利用指标,收获期测产.[结果]播期对春玉米各生育阶段的持续时间影响显著,生育期天数随着播期的推迟呈缩减趋势,合理播期应避免灌浆期的高温辐射和降雨量过多.除耗水量外,施氮量对其它各指标影响显著.叶面积指数、干物质积累量和产量均随灌水量增加而增加,随施氮量增加而上升,产量随播期的推迟而减少.S1I100N180处理产量最大,为16830 kg/hm2,比S2I100N240处理增产7.35％、节肥14.29％,比S3I100N180处理增产12.55％.水分利用效率随施氮量增大而增加,随灌水量增大而升高.S1I100N180处理水分利用效率为3.1 kg/m3,比S1I80N240处理高12.32％.氮肥偏生产力随施氮量增大而减小,S1I100N180处理氮肥偏生产力为93.5 kg/kg,比S1I100N120处理降低4.9％,但增产42.65％.[结论]综合产量和节水节肥因素,在本试验条件下适时早播(4月10日)有助于充分发挥水肥资源的潜力.在早播和充分灌水条件下,施用较低的氮肥量(N 180 kg/hm2)即可获得最高的产量.

针对宁夏引黄灌区灌溉水资源紧缺和土壤盐碱化等问题,于2018年8月至2019年3月在宁夏贺兰县通过田间试验研究了温室滴灌条件下地膜覆盖和深埋秸秆措施对土壤水、肥、盐及番茄产量的影响.试验设置T1(覆膜且埋秸秆)、T2(不覆膜但埋秸秆)、T3(覆膜但不埋秸秆)、T4(不覆膜不埋秸秆)4个处理.结果 表明:番茄全生育期内表层20 cm土壤含水率T1＞T2＞T3＞T4,深埋秸秆和覆膜均有利于提高表层40 cm土壤储水能力,抑制表层土壤返盐,尤其是地膜覆盖和深埋秸秆结合措施在表层40 cm具有明显的保墒控盐效果,相对T4处理,T1处理全生育期内表层土壤控盐水平提高27.94％;深埋秸秆措施能有效提高表层40 cm土壤养分水平;相对不覆膜且不埋秸秆措施,地膜覆盖或深埋秸秆结合措施提高了灌溉水分生产效率及番茄产量.综合考虑耕作层储水保墒、调控盐分和番茄产量,覆膜和深埋秸秆措施相结合效果最佳,且相对不覆膜不埋秸秆措施提高番茄产量13.65％、节水23.08％.