Effect of spatio-temporal deficit irrigation and nitrogen supply on water and nitrogen use of tomato

Integrating deficit irrigation into surface and subsurface drip irrigation as a strategy to save water in arid regions

Water shortage is one of the major constraints in vegetable production. Deficit irrigation is a sustainable technique that improves irrigation water use efficiency. Field studies were conducted during two growing seasons to evaluate the effects of deficit irrigation on plant growth, plant water status, productive response (curd yield and quality), irrigation water use efficiency (IWUE), and crop profitability of cauliflower. Nine irrigation treatments were used, applying 100%, 75% (moderate), or 50% (severe) of the irrigation water requirements (IWR) during the entire growing season (Continued Deficit Irrigation, CDI), or 75% and 50% of IWR during one of the following stages (Regulated Deficit Irrigation, RDI): Juvenility, curd induction, and curd growth. Severe deficit irrigation applied during juvenility and curd induction reduced the plant size, but it only led to a significant reduction of marketable yield (22%), and average curd size and weight if it was maintained throughout the crop cycle, supposing the highest IWUE (43.6 kg m−3). Moderate CDI or severe RDI during juvenility did not reduce significantly the curd yield compared to fully irrigated plants (4.4 kg m−2), thereby obtaining similar gross revenues (16,859 € ha−1) with important water savings (up to 24.3%), improving IWUE (up to 34.2 kg m−3).

Field research was done in two consecutive years to optimize deficit irrigation under different crop densities (low, medium, and high) using the ridge and furrow rainfall harvesting (RFRH) system. We demonstrate that applying deficit irrigation (375 m3 ha−1) at the flowering stage of maize grown at medium density (M: 75000 plant ha−1) under the RFRH system (MIF) can improve soil water storage (0–200 cm) at the bell, filling and flowering stages. MIF increased biomass by 10% and grain yield by 21%, thereby achieving a 17% increase in water use efficiency (WUE) and a 22% increase in precipitation use efficiency (PUE) compared with conventional flat planting (CKM). MIF also improved irrigation water use efficiency (IWUE) (9%) and irrigation water productivity (IWP) (46%) compared with no-irrigation under the RFRH system (MI0). We observed that applying deficit irrigation (750 m3 ha−1) at the bell and flowering stage (IBF) had positive effects on dry matter, leaf area, and evapotranspiration, but there were no significant increases in IWUE, IWP, WUE, biomass and grain yield compared with maize grown under IF at low, medium and high plant densities. The average net profit over the two years was 34% higher for MIF compared with the CKM treatment.

Effects of water and NPK fertigation on watermelon yield, quality, irrigation-water, and nutrient use efficiency under alternate partial root-zone drip irrigation

A sustainable strategy of managing irrigation based on water productivity and residual soil nitrate in a no-tillage maize system

In areas of finite groundwater resources, the groundwater used for irrigation must be used as efficiently as possible. Yields and water use characteristics of longer-maturity corn (Zea mays L.; 118-d relative maturity), shorter-maturity corn (97-d relative maturity), and grain sorghum [Sorghum bicolor (L.) Moench] under full and limited irrigation were evaluated from 1993 to 1996. Mean yield of longer-maturity corn was 15 bu/acre greater than that of shorter-maturity corn and 50 bu/acre greater than that of grain sorghum. Longer-maturity corn used the greatest amount of water, 3.4 in, greater than shorter-maturity corn or grain sorghum. Average water use rates were similar among the three crops. Mean water use efficiency for longer-maturity corn was not different from that of shorter-maturity corn; mean water use efficiency of grain sorghum was 1.4 bu/acre per in, less. Mean yield of fully irrigated crops was 15 bu/acre greater than that for crops under limited irrigation (replacing 70% of crop evapotranspiration [ET]). Water use efficiency of crops under limited irrigation was 0.7 bu/acre per in, greater than under full irrigation, but full irrigation of corn was more profitable than limited irrigation. These yields, average water use rates, and water use efficiencies indicate no justification for choosing shorter- over longer-maturity corn.

HighlightsAn Irrigation Scheduling Supervisory Control and Data Acquisition (ISSCADA) system was tested against a soil electrical conductivity (EC) based method for variable-rate irrigation (VRI).Soil EC was used to create irrigation prescription in EC-based VRI.ISSCADA generated VRI prescriptions using canopy temperature, soil water content, and weather data.ISSCADA-based VRI reduced irrigation water use and increased irrigation water productivity.Abstract. Use of variable-rate irrigation (VRI) technology has the potential to improve irrigation water use efficiency (IWUE). VRI hardware is commercially available and can be implemented in any center pivot or lateral move irrigation system. However, practical methods and algorithms for creating VRI prescriptions have become the bottleneck in accelerating the adoption of VRI. An Irrigation Scheduling Supervisory Control and Data Acquisition (ISSCADA) system for VRI was evaluated for two years in a humid region in the Mississippi Delta. The ISSCADA system was used to manage irrigation of soybeans for two seasons. In field practice, the ISSCADA system scanned the field for canopy temperature and collected soil water data from time domain reflectometers and weather data from a nearby weather station. The ISSCADA system automatically generated VRI prescription maps. The maps were modified to include plots managed using soil electrical conductivity (EC) based VRI prescriptions. Test results indicated that there was no difference in crop yield between EC-based VRI and ISSCADA-based VRI management. However, ISSCADA-based VRI management reduced irrigation water use and increased irrigation water productivity in comparison with EC-based VRI. There is great potential for the use of ISSCADA for VRI in humid regions. Keywords: Canopy temperature, Soil electrical conductivity, Soil moisture sensor, Soil water sensor, Soybean, Variable rate irrigation.

Water scarcity is becoming a critical problem in arid and semi-arid areas of the world, where part of the production of the main horticultural crops is located, as is the case of the Mediterranean area. Drought is one of the main limiting factors in agriculture and it is seriously affecting the production of horticultural crops. The improvement of water productivity in agriculture in general, and in horticulture in particular, can be achieved through the use of certain strategies. Deficit irrigation consists of the supply of water below the irrigation water requirements (IWR), so that there is a reduction in evapotranspiration. It can be done continuously (CDI) or regulated (RDI). With deficit irrigation, the irrigation water use efficiency can be improved, maintaining yield, and it could even lead to an improvement in the quality of the harvest. This study, carried out at the Cajamar in Paiporta Experimental Center (Valencia, Spain), analyzes the effect of deficit irrigation on four of the main cultivated horticultural crops, open field cultivated in the Mediterranean area: two of autumnal-winter crops (cauliflower and onion) and two spring-summer crops (pepper and watermelon). In the evaluation, the following parameters have been analyzed: plant growth and water status, yield, irrigation water use efficiency, quality of production and crop profitability. In the first season the CDI was tested, which allowed to establish the different growth stages for each crop, which were used in the following season for the RDI. In the four crops, the control plants (100% IWR) have shown an adequate water status, in terms of both relative water content and membrane stability index, while those subjected to a severe CDI, have shown the lowest values of both indexes. The negative effect of deficit irrigation on yield has been less important in autumn-winter crops than in spring-summer crops, especially in cauliflower. The CDI at 50% IWR has drastically reduced the marketable yield and, consequently, the gross revenue, although it has supposed an improvement in the irrigation water use efficiency for the autumn-winter crops. From the individual analysis of the crops, it can be stated that cauliflower yield obtained with CDI at 75% IWR or RDI at 50% IWR during the juvenile phase, has remained at levels similar to the control, improving the irrigation water use efficiency. In relation to onion, in case of severe water restriction, it would be advisable to apply CDI with 75% IWR or RDI at 50% IWR during bulb ripening, since these strategies have slightly decreased yield, improving the irrigation water use efficiency. In less restrictive conditions, RDI at 75% IWR during the bulb maturation has led to a satisfactory yield, with an increase in the irrigation water use efficiency. In Italian sweet pepper, the application of RDI to 75% IWR during the harvesting has resulted in a considerable reduction of the yield, and therefore, of the gross income, although with important water savings and increasing the fruit soluble solids and phenolic compounds content. By shortening the cultivation cycle until the beginning of September, when most of the marketable yield has already been harvested, significant water savings would be achieved, and the land could be used in other crops. CDI at 75% IWR and 50% IWR, or RDI at 50% IWR at harvesting have resulted in a high incidence of fruit affected by blossom-end rot. In watermelon the RDI application can be recommended, both 75% and 50% IWR, during the fruit ripening, since it has led to acceptable marketable yields. In general terms, it can be affirmed that the application of CDI and RDI in the four crops has not significantly affected the product quality, in terms of the analyzed parameters.

Scarcity of water is the most severe constraint for development of agriculture in arid and semi-arid areas. Under this condition, the need to use the available water economically and efficiently is unquestionable. Based on the actual crop need, irrigation management has to be improved so that the water supply to the crop can be reduced while still achieving high yield. A field experiment was carried out at Mehoni Agricultural Research Center, Raya Valley of Ethiopia, during 2016/17 season with objectives of determining the effect of deficit irrigation on Onion yield component and crop water productivity and the effect of Conventional, Alternate and Fixed furrow irrigation on yield and crop water productivity of onion. The treatment were five deficit irrigation levels (40, 55, 70, 85 and 100% ETc), and three furrow irrigation techniques (conventional, alternate and fixed furrow) were laid out in a random complete block design (RCBD) with three replications. The highest bulb yield was obtained at 100% ETc with conventional furrow method. In terms of irrigation and water use efficiency, 40% ETc deficit irrigation level application gave the highest irrigation water use efficiency and crop water use efficiency which was significantly superior to all other treatment. Among the irrigation water application methods, the highest water use efficiency was obtained with alternate furrow application method. On the other hand, the minimum water use efficiency was recorded with conventional furrow method. Alternative furrow irrigation (AFI) gave the highest crop water use efficiency and irrigation water use efficiency whereas conventional furrow irrigation (CFI) recorded the lowest. Better crop water use efficiency and irrigation water use efficiency were obtained in the AFI and fixed furrow irrigation (FFI), while the applied water in AFI was reduced by 50% of the CFI. Therefore, it can be concluded that increased water saving and associated water productivity can be achieved without significant reduction of yield in AFI with 100% ETc of irrigation level. AFI system appears to be a promising alternative. Key words: Alternate furrow, conventional furrow, deficit irrigation, fixed furrow, onion.

SUMMARYThe effects of partial rootzone drying (PRD) and rootstock vigour on dry matter accumulation and partitioning among leaves, shoots, fruits, frame and roots of apple trees (Malus domesticaBorkh. cvar Pink Lady) were investigated in 2005 near Caltavuturo, in Sicily. In a first field trial, trees on MM.106 rootstock were subjected to: conventional irrigation (CI), maintaining soil moisture above 0·80 of field capacity; PRD irrigation, where alternating sides of the rootzone received 0·50 of the CI irrigation water; and continuous deficit irrigation (DI), where 0·50 of the CI water was equally applied to both sides of the rootzone. In a second trial, trees on M.9 or MM.106 were subjected to CI and PRD irrigation. In trial 1, dry matter accumulation was markedly reduced by DI irrigation and to a lesser extent by PRD; PRD trees partitioned 20% less to leaves, 31% less to fruits and 24% more to woody components than CI trees; DI trees partitioned 14% less to current shoots and 18% more to fruits than CI and had the highest fruit:leaf ratio. In trial 2, there was no interaction between rootstock and irrigation treatments. MM.106 induced greater leaf, shoot, frame and root dry weights (DWs) than M.9, resulting in more vegetative growth and larger trees. PRD reduced leaf, shoot, frame and fruit DWs, while root DWs were similar to CI, and thus PRD trees were 18% smaller than CI trees. Neither rootstock nor irrigation affected dry matter partitioning among organs or root:canopy ratio, whereas PRD trees or trees on MM.106 showed better water use efficiency than CI and M.9, respectively. The results show that PRD trees did not activate drought tolerance strategies in terms of dry matter allocation that could improve acquisition of water resources, regardless of rootstock. PRD irrigation increased above-ground dry matter partitioning towards woody components at the expense of leaves and fruits.

The ridge and furrow rainfall harvesting planting system (RFRHP) where runoff is collected by plastic mulched ridges can improve the crop productivity in the semiarid areas of northwest China. During 2012–2014, we performed a field evaluation of the influence of RFRHP with supplementary irrigation (RI) on the water irrigation use and water use efficiency by maize in a semiarid climate using the following treatments: (1) no supplementary irrigation (RN); (2) irrigation during the trumpeting stage (RB); (3) irrigation during the blooming stage (RF); (4) irrigation during the trumpeting and blooming stages (RBF); and (4) traditional flat planting with border irrigation (CK). We found that although the irrigation volume was double under CK, the soil water content in the 0–120 cm soil layer did not differ significantly between the RFRHP with supplementary irrigation treatments and CK. The RFRHP with supplementary irrigation treatments reduced the irrigation water volume required (750–1125 m3 hm−2) and alleviated drought stress during key maize growth periods. The biomass, grain yield, and water use efficiency were significantly higher under RFRHP with supplementary irrigation, i.e., 6.0–8.7%, 15.4–25.8%, and 34.9–39.2% higher compared with CK, respectively, and 3.8–6.4%, 4.8–14.2%, and 9.2–12.7% higher compared with RFRHP with no supplementary irrigation. Under RFRHP with supplementary irrigation treatments, the irrigation water use efficiency was 1.5–3.9 times higher than that under CK. The irrigation water productivity levels under the RFRHP with supplementary irrigation treatments were ranked as follows: trumpeting stage > trumpeting and blooming stages > blooming stage. Compared with CK, RFRHP with supplementary irrigation significantly increased the out/input ratio and net income by 13.1–26.9% and 2600–3762 Chinese Yuan hm−2, respectively.

Strategies to enhance the efficient use of irrigation water require a major shift in irrigation and cropping systems. It was hypothesized that (i) replacing water-demanding crops such as corn silage with more drought-tolerant forages species, (ii) adoption of intercropping instead of monoculture, and (iii) use of alternative irrigation methods, may alleviate the water shortage in semi-arid regions, while producing high-quality forage. Adoption of drip irrigation (DRIP) and alternate furrow irrigation (AFI) reduced water consumption by 43% and 20%, respectively. Additionally, DRIP produced 11% more biomass than the conventional furrow irrigation. The intercropped ratio of 50% sorghum and 50% amaranth under DRIP maximized forage production and improved irrigation water-use efficiency (IWUE). Principal component analysis indicated that the DRIP increased the dry matter yield and IWUE, whereas the AFI improved the forage quality. The intercropped ratio of 75% sorghum and 25% amaranth demonstrated the highest yield stability and was considered superior cropping system regardless of the irrigation strategies. DRIP and AFI strategies were effective in reducing water consumption, with DRIP being the most water-efficient method. Intercropping sorghum and amaranth at a ratio of 50:50 under DRIP resulted in the highest forage yield and IWUE. While sole amaranth had the highest forage quality, intercropping sorghum and amaranth increased dry matter production with better forage quality than sorghum monoculture. Overall, the combination of DRIP and intercropping sorghum and amaranth at a ratio of 50:50 considered as a suitable strategy for improving forage yield and quality, as well as IWUE. © 2023 Society of Chemical Industry.

Effects of biochar and inorganic fertiliser applications on growth, yield and water use efficiency of maize under deficit irrigation

Reclaimed water irrigation has become an effective mean to alleviate the contradiction between water availability and its consumption worldwide. In this study, three types of irrigation water sources (rural sewage’s primary treated water R1 and secondary treated water R2, and river water R3) meeting the requirements of water quality for farmland irrigation were selected, and three types of irrigation water levels (low water level W1 of 0–80 mm, medium water level W2 of 0–100 mm, and high water level W3 of 0–150 mm) were adopted to carry out research on the influence mechanismS of different irrigation water sources and water levels on water and nitrogen use and crop growth in paddy field. The water quantity indicators (irrigation times and irrigation volume), soil ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N), rice yield indicators (thousand-grain weight, the number of grains per spike, and the number of effective spikes), and quality indicators (the amount of protein, amylose, vitamin C, nitrate and nitrite content) of rice were measured. The results showed that, the average irrigation volume under W3 was 2.4 and 1.9 times of that under W1 and W2, respectively. Compared with R3, the peak consumption of rice was lagged behind under R1 and R2, and the nitrogen form in 0–40 cm soil layers under rural sewage irrigation was mainly NH4+-N. The changes of NO3−-N and NH4+-N in the 0–40 cm soil layer showed the trend of declining and then increasing. The water level control only had a significant effect on the change of NO3−-N in the 60–80 cm soil layer. Both irrigation water use efficiency and crop water use efficiency were gradually reduced with the increase of field water level control. The nitrogen utilization efficiency under rural sewage irrigation was significantly higher than that under R3. Compared with the R3, rural sewage irrigation could significantly increase the yield of rice, and as the field water level rose, the effect of yield promotion was more obvious. It was noteworthy that the grain of rice under R1 monitored the low nitrate and nitrite content, but no nitrate and nitrite was discovered under R2 and R3. Therefore, reasonable rural sewage irrigation (R2) and medium water level (W2) were beneficial to improve nitrogen utilization efficiency, crop yield and crop quality promotion.

Mitigated CH4 and N2O emissions and improved irrigation water use efficiency in winter wheat field with surface drip irrigation in the North China Plain