Understanding the distribution of water and nitrate nitrogen in the soil profile is crucial for the reasonable operation of fertigation, and it is also fundamental for controlling and regulating nitrate nitrogen in the root zone, thereby meeting a crop’s requirements. The application rates of fertilizer and water directly influence this distribution of water and nitrate nitrogen. However, the effects in Aeolian sandy soil, a type of developing soil bordering deserts, remain ambiguous. In this study, field experiments for different drip fertigation treatments in Aeolian sandy soil were conducted to investigate the soil water distribution, as well as that of nitrate nitrogen. A completely randomized experimental design was implemented, encompassing three levels of irrigation amount: low (W1), medium (W2), and high (W3), and three levels of nitrogen application rate: low (F1), medium (F2), high (F3). After the completion of each irrigation treatment, soil samples were extracted at 10–20 cm intervals. The soil water and nitrate nitrogen contents in the profiles of these samples were measured. The experimental results revealed that increasing the nitrogen application rate facilitated the retention of greater amounts of water and nitrate nitrogen in the soil profile. However, with an increase in the nitrogen application rate, both soil water and nitrate nitrogen exhibited a radial tendency to move away from the drip emitter. Some moved upward and accumulated in surface soil near a ridge furrow, while some moved downward and remained in a deeper area approximately 30 cm horizontally from the emitter at depths of 40–60 cm. The uniformity of the water distribution decreased with increasing nitrogen application under low water conditions, with a reversal of this trend observed in medium and high water treatments. The effect of nitrogen application level on the uniformity of the nitrate nitrogen distribution was not significant. There was no significant correlation between the average soil water content and nitrate nitrogen content along the horizontal direction, however, a positive correlation existed in the vertical direction. In the whole profile, increasing the nitrogen application enhanced the correlation under low water conditions, but under medium and high water conditions, this trend was the opposite. This implies that, to avoid nitrate nitrogen leaching or limiting in a specific area, a moderate nitrogen application level is advisable. Under low water conditions, nitrogen application showed a positive effect on the nitrate nitrogen content, and a higher application is recommended. In cases of substantial water irrigation or rainy years, the nitrogen application rate should be decreased. Full article

Determining a suitable “dry sowing and wet emergence” water control program for cotton fields in the arid regions of Northwest China is of great significance in saving water resources, improving economic efficiency, and promoting sustainable development of agriculture. The objective of this study was to analyze the effects of different “dry sowing and wet emergence” water control treatments on dry matter accumulation, chlorophyll fluorescence, yield quality, and water productivity of cotton, and to determine the optimal “dry sowing and wet emergence” water control program for cotton growth in arid areas. A two-year experiment was carried out in 2021 and 2022 in mulched drip-irrigated cotton fields, with a total of 13 treatments of different seedling water quantities (2021: 67.5 mm, 90 mm, 112.5 mm; 2022: 6 mm, 10.5 mm, 15 mm) and different drip frequencies (frequencies means number of drops at seedling stage) (2021: one, two, three times; 2022: two times, four times) in the “dry sowing and wet emergence”. Results indicated a positive correlation between increased seedling water quantity and growth indexes. High seedling water quantity treatment demonstrated a 14.33% higher cotton yield than the low seedling water quantity treatment. In comparison with low-frequency treatment, the high-frequency treatment exhibited significantly larger cotton plant height, dry matter accumulation, and yield. Over two years, the average values increased by 8.69%, 16.4%, and 15.91%, respectively, with a 14.55% increase in the coefficient of photochemical quenching of the leaf blade (qP). The high frequency and larger amount of seedling water quantity treatments showed significantly higher irrigation water productivity, with increases of 39.2% and 70.2% compared to the winter irrigation control treatment. In summary, the appropriate “dry sowing wet emergence” water regulation mode (the first drip: 15 mm, the second drip: 4.5 mm, the third drip: 22.5 mm, the fourth drip: 15 mm) can ensure crop yield quality under the premise of significantly reducing the agricultural irrigation water, which can provide certain theoretical support for the green, efficient, and sustainable development of the local cotton industry. Full article

Due to the influence of the Asian southwest monsoon, seasonal drought is serious and water resources are scarce in the Yunnan province of Southwest China. More effective water-saving irrigation methods should be developed to solve the problem of water scarcity in the dry season. In this study, a subsurface drip irrigation method was used to improve the water productivity of tomato cultivation. Deficit irrigation was conducted. We controlled the lower limit of soil moisture at three different levels (55~65%, 65~75%, and 75~85% of the field capacity). The results indicated that the subsurface drip irrigation treatment significantly increased tomato height in the later stage of tomato growth. Due to the buried pipes, the root/shoot ratio was 8~18% higher for subsurface drip irrigation than for surface drip irrigation methods. Though the yields using subsurface drip irrigation methods were slightly lower than those obtained using surface drip irrigation methods, the tomato quality and water productivity improved significantly. The subsurface drip irrigation methods improved the water productivity by 8.5~21.8% at different soil moisture levels and improved the chlorophyll content by 9.1~17.3%. The VC, soluble sugar, soluble solids, and the ratio of sugar to acid increased by 6.5~15.2%, 7.3~21.6%, 4.1~6.6%, and 3.2~20.8%. This study also indicated that by optimizing the irrigation methods and patterns, water productivity and fruit quality could be improved by more than 50%. This research will be helpful for guiding irrigation during the drought season in the southwest monsoon area in Asia. Full article

The cultivation of drip-irrigated rice has resulted in lower yields. However, the decrease in rice yield under drip irrigation and its relationship with the existing water and N regime have not been fully explained. Research and development of optimized water and N-management techniques are crucial for increasing rice yield under drip irrigation. In this study, two irrigation treatments were set: conventional drip irrigation (DIO) and drip irrigation with water stress (DIS). Each irrigation treatment contained four N rates: urea N 240 kg ha⁻¹ (LN), urea N 300 kg ha⁻¹ (MN), urea N 360 kg ha⁻¹ (HN), and ammonium sulfate N 300 kg ha⁻¹ (AN). The soil’s ammonium and nitrate contents were measured on the 2nd and 28th days after N application at panicle initiation stage. At anthesis, the aboveground and root biomass of rice were measured. In heading and maturity stage the N content of aboveground was measured and the yield, yield components, and NPFP were assessed at maturity stage. The results showed the following: (1) On the second day after N application, the contents of soil NO₃⁻-N and NH₄⁺-N in the 0–10 cm soil layer were highest for both the DIO and DIS. On the 28th day after N application, the soil NO₃⁻-N content was highest at the 20–40 cm depth, while the soil NH₄⁺-N content was still highest at the 0–10 cm depth. (2) The aboveground and root biomass in DIO treatment were significantly higher than in DIS. Furthermore, the root biomass at the 0–10 cm depth was significantly greater than at the 10–50 cm depth for both the DIO and DIS treatments. In the DIO treatment, the root biomass at the 10–50 cm depth was significantly higher with the HN and AN treatments compared to MN. However, in the DIS treatment, the root biomass at the 10–50 cm depth did not show significant differences between the MN, HN, and AN. (3) N accumulation in rice was significantly higher for the DIO treatment compared to the DIS treatment. Under the same irrigation treatment, the N accumulation in rice was highest in the AN and lowest in the LN. The PrNTA and PrNTC in DIS were significantly higher than in DIO, while the PoNAA and PoNAC were significantly lower in DIS. (4) The number of panicles, spikelets per panicle, seed-setting rate, 1000-grain weight, and grain yield were significantly lower in DIS. Under the DIS, these parameters were not significantly different among the MN, HN, and AN. In the DIO, the seed-setting rate, 1000-grain weight, and yield were not significantly different between the HN and AN, but were significantly higher than in the MN and LN. (5) NPFP was significantly higher in the DIO compared to the DIS. Among the different N rates, NPFP was highest with the AN treatment and lowest with the LN. In summary, under drip irrigation, there was a mismatch between soil mineral N and the distribution of rice roots, leading to reduced N accumulation and utilization in rice, ultimately impacting yield formation. Increasing N application and soil ammonium nutrition can improve rice yield under drip irrigation. However, optimizing N fertilizer management may not increase rice yield further when irrigation is further limited. Full article

Uneven soil moisture and nutrient distribution before and after intercropping limits apple cropping system productivity in the western Shanxi–Loess Plateau area. To address this issue, a field trial was conducted between 2020 and 2021 to study the effects of different water and fertilizer management practices on soil moisture, nutrients, and root distribution, as well as the overall effectiveness of the apple–maize and apple–soybean intercropping systems during crop replacement. The experiment involved two irrigation methods: drip (D) and flood (M) irrigation. Three irrigation levels included rain-fed without irrigation (W0), and 50% (W1) and 80% (W2) of field capacity (Fc). Three fertilizer treatments included no additional fertilizer application (F0), 375 kg∙hm⁻² (F1), and 750 kg∙hm⁻² (F2), in addition to a control (CK) without irrigation or fertilization. The soil water content (SWC) decreased after the crop replacement. Additionally, nitrate nitrogen (NN), ammonium nitrogen (AN), and organic matter (OM) content levels in all treatments increased, whereas total phosphorus (TP) content decreased. The soil layer with crop roots moved downward after crop replacement, and partial fertilizer productivity (PFP), irrigation water use efficiency (IWUE), and water use efficiency (WUE) were decreased under both irrigation treatments. Principal component analysis showed that the W2F2 treatment had the highest benefit from crop combination across both irrigation treatments during the crop replacement period. According to our results, to optimize the benefits of apple-crop intercropping, drip irrigation with complete water supply and flood irrigation with incomplete water supply are recommended during crop replacement. In addition, an upper irrigation limit of 80% Fc with 750 kg∙hm⁻² fertilization is recommended for optimal water and fertilizer regulation. Full article