Agricultural Water Management最新文献

Intelligent fertigation is a sustainable solution for optimising water and fertiliser input, thus minimising environmental pollution in vegetable cultivation facilities and reducing labour costs in agricultural practices. It is important to optimise irrigation scheduling parameters to specific crops to ensure water and nutrient use efficiency. A field experiment was conducted in Shouguang, Shandong Province, to investigate the effects of irrigation scheduling with different treatments (farmer drip irrigation FI, intelligent irrigation II1, and intelligent irrigation II2) on tomato growth, irrigation water and nutrient use efficiency over two growth seasons. Intelligent irrigation II1 and II2 utilised FDR sensors to control the moisture range within 80–95% and 80–85% field capacity (FC) for automatic irrigation scheduling, respectively. Intelligent irrigation (II1 and II2 treatments) reduced irrigation rate by 24.3–63.8% in comparison with FI treatment, significantly increasing total dry matter accumulation, nutrient uptake, yield and fruit quality of tomato. II2 treatment further reduced the irrigation rate by 31.6–32.3% compared to II1 treatment, with no significant difference in tomato yield and quality. Root dry matter, root-shoot ratio, 0–2 mm diameter root length and root surface area, 0–1.5 mm diameter root tips, and >3.5 mm diameter root volume were significantly increased under intelligent irrigation treatments. Positive correlations between irrigation water productivity; nitrogen, phosphorus, and potassium use efficiency; and the indices of length, surface area, tips, and volume of roots were highly significant. Intelligent fertigation system (IFS) maintained soil moisture within a suitable range through high-frequency irrigation scheduling, promoted the growth of 0–2 mm diameter roots, which were responsible for absorbing, acquiring, and transporting water and nutrients in the soil, and reduced water loss and nutrient leakage. Taken together, the intelligent fertigation system presented herein is an effective fertigation strategy to improve irrigation water and nutrient use efficiency.

Given the current scarcity of freshwater resources, it is imperative to explore new agricultural management options to sustainably enhance food production. Desalinated seawater (DSW) presents a promising solution for irrigation in water-stressed regions. However, its application in perennial crops has been poorly assessed, potentially posing challenges to existing cultivation practices due to higher associated costs, salinity, and the presence of potentially harmful elements, notably boron (B). To address these uncertainties, a three-year experiment was conducted to evaluate the short-term effects of irrigation with DSW on a ‘Rio Red’ grapefruit orchard. Four irrigation treatments were assessed: DSW, freshwater (FW), a 1:1 mixture of DSW and FW (MW), and DSW with reduced B concentration (DSW–B). At present, the young age of the trees (3.5 years) and their grafting onto a five-year-old rootstock at the beginning of the experiment likely facilitated rapid foliar mass development and prevented the accumulation of phytotoxic elements up to critical levels. However, local DSW consistently exceeded recommended citrus thresholds for B (0.5 mg L^–1), sodium (Na⁺; 115 mg L^–1), and chloride (Cl^–; 250 mg L^–1) in irrigation water, resulting in significant concentrations of B (2.1 mg kg^–1), Na⁺ (504 mg L^–1) and Cl^– (476 mg L^–1) in soil. Moreover, these levels led to concentrations in leaves close to defined thresholds in the case of Na⁺ (0.25 g 100 g^–1), and exceeded them in the case of B (>250 mg kg^–1). Although fruit quality remained unaffected, variability in yield among trees and the cost disparity between water resources, resulted in slight fluctuations in the income-outcome balance during initial cultivation years. Our findings offer insights into the irrigation of sensitive crops with DSW, aimed at mitigating potential soil and plant harm from early accumulation of phytotoxic elements. Further research is warranted to explore the impact of both single and sustained DSW usage for irrigation purposes.

This paper highlights the evolution and impact of the SWAP model (Soil – Water – Atmosphere – Plant), which was initiated by R.A. Feddes and colleagues fifty years ago, in 1974. Since then, the SWAP model has played a crucial role in the advancement of agrohydrology. This paper highlights some major advances that have been made, especially focussing on the last fifteen years. The domain of the SWAP model deals with the simulation of the soil water balance in both unsaturated and saturated conditions. The model solves the Richards equation using the water retention and hydraulic conductivity functions as described by the Van Genuchten – Mualem equations. Bimodal extensions of the Van Genuchten - Mualem relationships have been implemented, as well as modifications near saturation and addressing hysteresis. An important sink term in the Richards equation is root water uptake. Crop development plays an important role in a robust simulation of root water uptake. That is why a link has been made with the dynamic crop growth model WOFOST. Instead of using a prescribed crop development, a distinction between potential and actual crop development is calculated by reducing the potential photosynthesis as a result of water or oxygen stress. Since the early days of SWAP, empirical and macroscopic concepts have been used to simulate root water uptake. Recently two process-based concepts of root water uptake and oxygen stress have also been implemented. Another important sink-source term in the Richards equation is the interaction with artificial drains. In SWAP, drainage can be simulated by either using prescribed or simulated drain heads and simulation of controlled drainage with subirrigation is possible. Finally, we briefly elaborate on three studies using SWAP: water stresses in agriculture in the Netherlands, regional water productivity in China, and controlled drainage with subirrigation. We finish discussing promising developments for the near future.

Water-stressed regions like Kenya rely on saline water sources, which can pose serious health hazards if not treated. While desalination is a burgeoning solution, safe disposal of desalination brine is often infeasible or too expensive. To circumvent this disposal challenge, we examine the maximum desalination recovery ratio (RR_max) for which desalination brine can safely be reused for many agricultural applications. Water samples from the Mara Triangle and data from past studies were collected and analyzed to measure contaminant concentrations against established safety limits of salinity and potentially hazardous elements for multiple agricultural use cases. The results suggest that high water recoveries were possible in the Mara Triangle, with the maximum recovery ratio reaching greater than 94% and 98% for crop irrigation and livestock watering, respectively. Brine reuse in this region was mostly limited by salinity, with Boron content ranking second. The most salt-tolerant crops (i.e., barley, sorghum, and wheat) were shown to be cultivable in all locations. According to calculations of the Heavy Metal Evaluation Index, groundwater in the Mara Triangle was generally safer for direct use by all users than the surface waters sampled in the past Lake Victoria and Nairobi studies.

In both arid and semi-arid regions, adopting field mulching can effectively optimize soil moisture distribution, enhance crop yields, and improve water productivity. While acknowledging its advantages, field mulching seems insufficient for maintaining high crop productivity due to the increasing frequency of extreme weather. Furthermore, drought often coincides with critical crop growth stages, necessitating the implementation of agricultural irrigation to ensure normal crop growth. Accordingly, we conducted a three-year field experiment from 2021 to 2023 including three typical field mulching methods (no mulching, NM; straw mulching, SM; plastic film mulching, FM) and three supplementary irrigation strategies (irrigated at the branching stage (V4), W1; irrigated at the pod-filling stage (R2), W2; irrigated at both the V4 and R2 stage, W3). Throughout the entire growth period, we monitored soil moisture conditions for each treatment, measured leaf physiological parameters at crucial growth stages, and assessed soybean yields and water productivity (WP). Our findings indicated that, relative to SM and NM, FM maintains optimal soil moisture balance, augments chlorophyll content, and enhances photosynthesis, resulting in an average yield increase of 17.0% and 38.3% over three growing seasons. Additionally, supplementary irrigation also significantly affects the growth and seed yield of soybean. FMW2 achieved the higher seed yield (4307.5 kg ha⁻¹, 3-year averaged), had insignificant difference with the highest seed yield of 4568.6 kg ha⁻¹, both significantly higher than other treatments. Similarly, the leaf area index, chlorophyll content, net photosynthetic rate (P_n) and transpiration rate (T_r) also presented insignificant difference between FMW2 and FMW3, while WUE_leaf (P_n/T_r) of FMW2 obviously higher than that of FMW3. As a result, FMW2 achieved the highest WP of 12.2 kg ha⁻¹ mm⁻¹ over the three growing seasons, compared to the three-year average of the other treatments, the increase ranges from 5.6% to 46.7%. In summary, the FMW2 treatment optimized water distribution to meet the water demands of soybeans during the reproductive growth stages, achieving a beneficial balance between soybean seed production and WP by regulating leaf functional parameters. Future research will explore more specific irrigation scheduling techniques (e.g., precision irrigation, deficit irrigation, and sensor-based irrigation management systems) while integrating innovative agricultural film materials (e.g., biodegradable films) to further enhance crop resilience and productivity under evolving climatic conditions.

Adopting drought-tolerant (DT) cultivars is an effective strategy to sustain maize (Zea mays L.) production under water shortage. Optimizing plant density is an important management practice for improving maize yield. In a two-year field trial, the response of yield, actual evapotranspiration (ET_{c act}), and water productivity (WP) to plant density (6, 7.5, 9 plants m⁻²) was assessed under irrigated and rainfed conditions using a DT (ZD958) and a drought-susceptible (DS, ZY309) maize cultivar, and additionally, the comparison of soil water depletion will be conducted among soils growing different DT maize varieties. Under rainfed, average yield, ET_{c act}, and WP were 24.7%, 8.6% and 14.8% greater in ZD958 than ZY309, respectively. When density increased from 6 to 9 plants m⁻², for ZD958 and ZY309 ET_{c act} remained relatively constant, whereas their yield and WP first increased and then decreased and ultimately reached their maximum at 7.5 plants m⁻². Under irrigation, increasing density (6–9 plants m⁻²) significantly increased yield and WP for ZD958, but for ZY309, yield and WP were not significantly impacted. Yield across seasons did not differ between cultivars at 6 and 7.5 plants m⁻², and ZD958 had a 10.2% yield advantage over ZY309 at 9 plants m⁻². The findings imply that DT cultivar showed greater high density tolerance than DS cultivar and thus higher optimal density under irrigation. Under rainfed, both cultivars had similar density tolerance and optimum density, whereas DT cultivar had stronger drought tolerance than DS cultivar, which could explain DT cultivar’s greater yield and WP. This study indicate that DT cultivar showed higher and more stable yields than DS cultivar across rainfed and irrigated conditions when grown at optimal densities. Thus, sustainable maize production could be achieved by adopting DT cultivars and optimizing density for different conditions in the study region.

Stable isotopes of hydrogen and oxygen are used in agriculture to investigate the water sources used by crops. Yet, isotopic research on irrigated orchards is still scarce. We investigated the isotopic variability in an apple tree plantation in the Eastern Italian Alps (South Tyrol) during the growing seasons 2020 and 2021. The orchard was subject to an irrigation trial, whereby a drip system was triggered at different soil water potential thresholds at two treatment types: full irrigation (FI, −30 kPa) and deficit irrigation (DI, −60 kPa). On a bi-weekly basis, we sampled precipitation, river water, and groundwater used for irrigation. At both FI and DI, we sampled soil at different depths and bark-devoid branches, and cryogenically extracted their water. Isotopic analyses revealed large differences in δ¹⁸O values of soil water belonging to the two irrigation treatments, particularly during the irrigation period (up to 8.9‰). In xylem water, the differences were much smaller (up to 1.6‰). Mixing models (EEMMA) estimated a larger groundwater (vs. rainwater) fraction in the shallow soil (5–10 cm) at FI (25–55%) than at DI (0–5%), compatible with a larger presence of irrigation water in the former. DI plants had a deeper root water uptake (32.0 ± 11.9 cm) than FI ones (19.3 ± 14.5 cm) during the irrigation period. This agreed with the results of mixing models (IsoSource) that estimated a larger use of deeper (60–65 cm) soil water (42 ± 18%) and a lower use of shallow soil water (13 ± 6%) for DI than for FI (34 ± 26% and 27 ± 26%) during the same period. This root water uptake plasticity explains the lacking evidence of physiological stress in sap flux records at DI and supports the potential for further improvements of precision irrigation in similar climatic and edaphic settings.

Due to the adverse effect of global climate change on agricultural water management, maintaining soil moisture in the root zone is essential for optimal crop productivity. For effective irrigation, we used organic mulching to increase the yield and water productivity (WP) of Valencia orange in arid/desert climates. Here, the effect of rice straw mulching and irrigation rates [100, 85, and 70% of evapotranspiration reference (ETc)] on nutrient contents, quality, and yield of orange trees was evaluated. Under field conditions, the application of straw mulch significantly increased the concentration of some essential elements and photosynthetic pigments but reduced proline contents in orange leaves. Soil mulching significantly increased fruit and inflorescence retention, and resulted in a higher number and weight of fruit on branches, without compromising their taste or texture, compared to the treatment without mulching. Both irrigation and mulching also affected crop productivity and water use efficiency (WUE). This was evident when yield/fed increased by 22.7–23.8, 20.7–31.5, and 6.2–16.9% under mulching at 100, 85, and 70% ETc, respectively, compared to traditional conditions at 100% ETc without mulch. Although the maximum WUE under rice straw mulch was 5.72–5.84 kg/m³ at 70% ETc, it was 5.31–5.40, and 4.57–4.64 kg/m³ at 85, and 100% ETc, respectively. Organic mulching showed superior results with respect to increasing yields and WP, while saving 15.4% water and comparable benefit/cost with the traditional irrigation when orange trees were irrigated with 85% ETc. Together, this study could be a promising strategy for climate change adaptation and sustainable water management.

Accurate estimation of evapotranspiration (ET) at high spatial resolution is crucial for drought monitoring and water resources management, but currently available remote sensing ET products generally have coarse spatial resolution (≥1000 m). To estimate ET at a high spatial resolution, Landsat images, Global Land Surface Satellite (GLASS), Moderate Resolution Imaging Spectroradiometer (MODIS), and meteorological forcing data were integrated, and the surface energy balance (SEBS) model was employed to calculate the 16-day average ET at 30 m resolution for China’s Tarim River Basin, spanning from 2009 to 2018. The results indicated that the average 16-day ET estimates correlated well with ground observations for land and water surfaces (root mean square error (RMSE) for land = 0.92 mm day⁻¹, RMSE for water = 1.63 mm day⁻¹, mean bias for land = 0.3 mm day⁻¹, mean bias for water = 0.52 mm day⁻¹). Cross validation with GLASS, ETMonitor, and Penman-Monteith-Leuning (PML_V2) ET datasets revealed an overall increasing trend for all four products (PML_V2 = 6.277 mm year⁻¹, GLASS = 2.185 mm year⁻¹, ETMonitor = 3.258 mm year⁻¹, SEBS = 1.441 mm year⁻¹), demonstrating good spatial consistency. The consistent increasing pixels were primarily distributed in the northern, southwestern, and southeastern mountainous regions, accounting for 22.8%, while 0.29% of the consistent decreasing pixels were mainly concentrated in the central desert and mountain-front oasis areas. Inconsistent pixels accounted for 76.9%, with 2.34% of the inconsistent decreasing pixels exhibiting a scattered distribution, while 37.28% of the inconsistent increasing pixels were mainly found in the central desert and some oasis areas. Furthermore, SEBS ET trend analysis indicated that the oasis area experienced more pronounced changes than the mountainous and desert areas during the 2009–2018 period. The SEBS ET estimated in this study can provide high-precision data support and a reference for future research on the water resources management.

Intercropping has been widely recognized to have great advantages in terms of increasing yield, controlling pests and diseases, and saving land, particularly in developing countries. Regulated deficit irrigation reduces water consumption and improves water productivity (WP). However, it is unclear whether the combination of intercropping and deficit irrigation could improve crop yield and WP simultaneously. In this experiment, three planting modes, including forage maize (Zea mays L.) monoculture (M), lablab bean (Lablab purpureus L.) monoculture (L), and maize-lablab bean intercropping (ML) were used. Six irrigation modes were set for each planting mode, including severe water deficit (W1), late water deficit (W2), alternate water deficit (W3), late moderate water deficit (W4), early moderate water deficit (W5), and full irrigation (W6). Results showed that compared with M, the ML treatment significantly increased the fresh forage yield (9.8%–17.0%), hay yield (9.5%–13.1%), crude protein yield (22.9%–25.9%), and WP (7.8%–8.7%). The W5 treatment achieved similar fresh forage yield, hay yield, and crude protein yield as that of the W6 treatment but reduced irrigation water by 25% and increased the WP (21.9%–24.8%). Intercropping achieved a high-water equivalence ratio (WER;1.52–1.81) and land equivalence ratio (LER;1.56–1.84), indicating its advantages over monocultures. The W6 treatment had the lowest WER and LER, suggesting that excessive irrigation can reduce the efficiency of utilizing land and water resource in maze-based forage production. Among all treatments, ML–W5 achieved the highest net income and output to input ratio. Overall, intercropping of forage maize and lablab bean with moderate deficit irrigation at an early stage could be used as a high-yield and efficient forage production system in the arid areas of northwest China.