Reduce Irrigation Demand Research Articles

A multi-objective optimization approach to simultaneously halve water consumption, CH4, and N2O emissions while maintaining rice yield

Sustainable rice farming practices are urgently needed to meet increasing food demand, cope with water scarcity, and mitigate climate change. Traditional farming methods that prioritize a single objective, such as increasing crop yield, reducing irrigation water consumption, or minimizing greenhouse gas (GHG) emissions, have proven to be insufficient. Simultaneously optimizing multiple competing rice farming objectives remains less explored. The present study aimed to increase current rice yield, reduce irrigation water consumption, and tackle the dilemma to reduce GHG (CH4 and N2O) emissions at once. Using a heuristic and holistic method, we optimized farm management, focusing on irrigation regimes, sowing window, fertilization rate, tillage depth, and their interactions. We calibrated and validated the process-based DeNitrification–DeComposition (DNDC) model with 5 years of eddy covariance observations in a rice paddy site. The DNDC model was integrated with a Pareto-based non-dominated sorting genetic algorithm (NSGA-III) to solve the multi-objective optimization problem. Results show that current farm management practices have failed to achieve the potential yield and imposed high environmental costs in the form of water use (604–810 mm/yr) and GHG emissions (CH4: 186–220 kg C/ha/yr; N2O: 0.3–1.6 kg C/ha/yr). By contrast, our new approach suggested that the optimized management could maintain or even increase current crop yield to its potential (∼10 t/ha), while reducing irrigation demand and GHG emissions by >50 %. Our results suggest that earlier sowing, combined with improved irrigation practices, may play a crucial role in maximizing crop yield and potentially providing environmental benefits. We found that the optimal proportion of non-flooded days was around 54 % of the growing season length, and the optimal stage for non-flooding days was the vegetative stage. Our approach could further be applied to evaluate the environmental sustainability of farming systems under various climate and local conditions, and to guide policymaking and farming practices.

Impact of biochar amendments on soil water and plant uptake dynamics under different cropping systems

AbstractApplication of biochar amendments in agricultural systems has received much attention in recent years. In this study, we assess the 5‐year impacts of biochar application on soil water and plant interactions for an irrigated fresh market tomato (Solanum lycopersicum) and a rainfed pasture (Poaceae) cropping system. In particular, we focus on three varieties of locally produced biochar from agricultural waste materials—almond shell, walnut shell, and almond pruning residues that are pyrolyzed using a mobile pyrolysis unit. We used the soil hydrological model HYDRUS‐1D to explicitly track seasonal and annual soil water fluxes through changes in water retention, drainage, evaporation, and plant water uptake under biochar application. Modeling results show that the application of biochar at 5% increased soil water availability within the top 20 cm for a rainfed system, irrespective of biochar amendment type. This is clearly indicative of higher plant water uptake and greater water use efficiency (WUE) under biochar application. In contrast, a similar biochar amendment for the irrigated system did not affect WUE, instead reducing seasonal soil evaporation loss and thereby reducing irrigation demand. In both cropping systems, year‐to‐year variability in precipitation significantly impacted the total amount of water saved under biochar application with certain amendments retaining more water than others. Given that biochar application increased water retention irrespective of cropping systems, we further used a simple approach to determine yield trade‐off, if any, between control and biochar treatments. Our economic balance clearly demonstrates that the water saved by amending soil with biochar does not offset the yield disparity if compensated with carbon credits and therefore, application of biochar should be actively considered for both its direct and indirect benefits to potential greenhouse gas mitigation (e.g., diverting orchard waste from open burning), water savings, and soil health.

Modelling the trash blanket effect on sugarcane growth and water use

The traditional practice of burning at the pre-harvesting of sugarcane has being phased-out in Brazil, resulting in the maintenance of a crop s residue layer on soil surface, namely the Green Cane Trash Blanket (GCTB). New technologies for electricity and second-generation ethanol (2G) production from crop residues have raised the question on what would be the optimum amount of crop residue left on the field to keep the agronomic and environmental benefits of GCTB. To support informed decision making on sugarcane trash management, we updated, evaluated and applied a new version of the SAMUCA model to simulate the sugarcane growth and water use under the GCTB effect. The updated model was calibrated and parameterized for bare soil and GCTB conditions and evaluated across different Brazilian regions. Thirty-year simulations were then conducted with the updated model to quantify the effects of GCTB on sugarcane growth and water use where sugarcane is traditionally grown in Brazil. The updated version of SAMUCA model showed equal or superior performance when compared with widely-used process-based models for sugarcane. Based on our 30-year simulations, the GCTB exhibited a high probability to promote a beneficial effect on sugarcane yields in dry climates (>90%), with the potential for increasing, on average, 14 ton ha−1 of fresh cane yield in Petrolina, Brazil. Although the beneficial effect on yields were not significant in humid regions, the maintenance of 12 ton ha−1 of GCTB was associated with a high probability (>87%) in reducing the water use of sugarcane cropping system by 89 mm, on average, potentially reducing irrigation demand in the early stages of crop development while protecting crop production under dry spell events. The new version of SAMUCA model offers as a tool for decision making on mulch management in sugarcane plantations.

Restoring soil health to reduce irrigation demand and buffer the impacts of drought

Restoring soil health to reduce irrigation demand and buffer the impacts of drought

Reducing the Excessive Evaporative Demand Improved the Water-use Efficiency of Greenhouse Cucumber by Regulating the Trade-off between Irrigation Demand and Plant Productivity

Although atmospheric evaporative demand mediates water flow and constrains water-use efficiency (WUE) to a large extent, the potential to reduce irrigation demand and improve water productivity by regulating the atmospheric water driving force is highly uncertain. To bridge this gap, water transport in combination with plant productivity was examined in cucumber (Cucumis sativus L.) grown at contrasting evaporative demand gradients. Reducing the excessive vapor pressure deficit (VPD) decreased the water flow rate, which reduced irrigation consumption significantly by 16.4%. Reducing excessive evaporative demand moderated plant water stress, as leaf dehydration, hydraulic limitation, and excessive negative water potential were prevented by maintaining water balance in the low-VPD treatment. The moderation of plant water stress by reducing evaporative demand sustained stomatal function for photosynthesis and plant growth, which increased substantially fruit yield and shoot biomass by 20.1% and 18.4%, respectively. From a physiological perspective, a reduction in irrigation demand and an improvement in plant productivity were achieved concomitantly by reducing the excessive VPD. Consequently, WUE based on the criteria of plant biomass and fruit yield was increased significantly by 43.1% and 40.5%, respectively.

Shifting planting date of Boro rice as a climate change adaptation strategy to reduce water use

Suitable adaptation strategies for dry season Boro rice cultivation under future climate change scenarios are important for future food security in Bangladesh. This study assessed the effect of shifting trans−/planting date of dry season Boro rice as an adaptation strategy, with focus on water requirements under future climate scenarios. Potential crop water requirement, effective rainfall and irrigation requirement to satisfy crop evapotranspiration of Boro rice were estimated using CropWat 8.0 for early, normal and late planting dates for 2050s and 2080s. Future climate scenarios were constructed using five global circulation model (GCM) outputs for RCP 4.5 and 8.5 by statistical downscaling and bias correction. Number of days exceeding the threshold temperatures (maximum of 35 °C and minimum of 25 °C) was counted for critical period of Boro rice to understand compatibility of the changed planting dates. Results indicate that late planting can substantially reduce irrigation demand by increasing rainfall availability during Boro growth duration, but the option is very limited due to both day- and night-time heat stress. An early planting, on the other hand, accounts for high water demand but ensures suitable temperature during the critical growth stages of the crop. The normal planting dates show the possibility of day-time heat stress. So, late planting of temperature-tolerant cultivars or early planting of high-yielding varieties would be recommended based on local water availability. However, adjustment of the planting date is currently limited because high temperature-tolerant cultivars are not available in the study region.

Reducing the excessive evaporative demand improved photosynthesis capacity at low costs of irrigation via regulating water driving force and moderating plant water stress of two tomato cultivars

Although atmospheric evaporative demand is increasingly recognized as significant roles in coupling water transport and carbon acquisition, potentials to reduce irrigation demand and improve photosynthesis performance via regulating evaporative demands is highly uncertain. To bridge this gap, plant water status in combination with photosynthetic carbon acquisition under contrasting evaporative demand was examined in two cultivars of tomato (Solanum lycopersicum L.). Experiments were conducted from May to August in 2016. Evaporative demand gradients were achieved via regulating vapor pressure deficit (VPD) at two adjacent greenhouses of similar characteristics: High VPD was maintained in natural greenhouse condition without environmental regulation (Control); Moderate VPD was achieved by artificially humidification when evaporative demand exceeded optimal ranges (Humidification). VPD regulation by humidification reduced the excessive driving force for water flow, which efficiently prevented the declines in plant water potential and alleviated hydraulic limitation. Transpiration rate and irrigation demand over experimental period were substantially reduced via reducing evaporative driving force in humidification treatment. Moderation in plant water stress sustained stomatal openness for CO2 acquisition and utilization. Photosynthetic capacity was significantly improved by humidification, as indicated by the substantial increases in photosynthesis rate(Pn), rubisco carboxylation capacity(Vcmax), maximum electron transport capacity (Jmax) and net assimilate rate (NAR). At long-term scales, fruit yield was increased by 14.6% and 16.7% for two cultivars. Whole plant biomass was increased by 22.6% and 16.9% for two cultivars. Plants irrigation amount in humidification treatment over the experimental period was significantly saved by 16.9% and 17.4% for two cultivars. Taken together, VPD regulation had great potentials to reduce irrigation demand and improve photosynthetic capacity via reducing water driving force and sustaining stomatal function. The present study provided novel information to improve photosynthetic and reduce irrigation demand for sustainable crop production.

Woody organic amendments for retaining soil water, improving soil properties and enhancing plant growth in desertified soils of Ningxia, China

Extreme soil degradation is one of the most serious problems affecting dryland ecosystem health and agricultural production globally. This study was conducted to investigate the potential for using woody amendments to improve soil moisture availability, soil microbial activity, soil fertility, and plant growth in desertified soils in Ningxia, China. Soil amendments of wood chips derived from tree branches of four readily available tree species (poplar, elm, pagoda tree, and grapevine), were evaluated and compared with more commonly used wheat straw, rice husks, and cow manure, using replicated microcosm experiments. Different types, concentrations, and application techniques of woody and non-woody organic amendments were compared for their impacts on soil moisture, soil chemistry, microbial activity, and plant growth. The treatments with woody organic materials incorporated into the soil consistently demonstrated an improvement in soil water status, increased organic C content, and improved soil fertility, and also resulted in enhanced microbial activity, and wheat growth. Although surface mulch increased soil water storage and enhanced wheat growth, it did not effectively improve soil microbial activity as compared with wood incorporated into the soil. Differences in placement and type of amendment differ markedly in their effects on physical, chemical and biological soil responses. A combination of 5% poplar wood chips incorporated into the soil with a lattice of twigs over the soil was ideal for simultaneously maximizing soil water availability, encouraging microbial activity, and maximizing wheat yield. In conclusion, woody materials from locally available trees can serve as a valuable amendment for desertified soils in Ningxia and other places of Northern China by increasing rainfall capture, reducing irrigation demand, improving soil health and promoting higher crop yields.

Farmer adaptation of intermittent flooding using multiple-inlet rice irrigation in Mississippi

Although intermittent flooding of rice (Oryza sativa L.) has been shown to significantly reduce irrigation demand, farmer adoption is limited in the United States where continuous flooding remains standard practice. This limited extent of adoption stems in part from a number of scalability and agronomic concerns. This study used replicated trials established in farmer-managed fields to determine if intermittent flooding can be successfully adapted to commercial-scale rice production in Mississippi. When intermittent flooding was coupled with multiple-inlet rice irrigation (MIRI), the quantities and qualities of yields were maintained or increased for five commercial rice varieties and one hybrid, relative to continuously-flooded controls. Only CL151 exhibited a decrease in total head rice when milled, this after being subjected to five or more wetting and drying cycles over ≈80 day flood periods. Water use over three years averaged 32% less than comparable MIRI systems not using intermittent flooding. These results demonstrate that intermittent flooding can be successfully adapted by producers to commercial-scale and that 600mm irrigation is an achievable goal for rice grown on clay soils in Mississippi. The positive yield responses of CL162 to intermittent flooding and pre-flood urea-nitrogen support research showing that rice benefits from carefully managed wetting- and drying-periods when used in conjunction with effective pest management. The success of these producers at adapting intermittent rice flooding to commercial scale can be attributed in part to their having comprehensive weed and disease management programs, proficiency in using MIRI, and reliable irrigation systems with ample well capacities that allowed rapid flood establishment. Even partial adoption of intermittent rice flooding can increase rainfall capture and reduce demand for irrigation. In turn, this could help to alleviate overdraft of the Mississippi River Valley Alluvial aquifer, a resource of national and international significance.

An interactive multi-scale integrated assessment of future regional water availability for agricultural irrigation in East Anglia and North West England

A multi-scale approach has linked farm level decisions with regional water availability assessments that allow for environmental water needs and the competing demands for water. This is incorporated within a user-interactive software tool, enabling the impact of a range of variables to be easily examined. Climate change leads to increased potential irrigation demand in East Anglia and North West England. Under baseline socio-economic conditions, results suggest that such increased future water demands can be met in the North West, but in the drier East Anglian region are counter to the decreasing water availability under all climate scenarios. The decreasing availability is moderated or exacerbated according to the environmental priorities of the future socio-economic scenarios. Under economically focussed regional futures, water supply availability increases at the expense of the environment, despite high water demands. Under environmentally focussed futures, demand restrictions are needed due to the further decreased water availability as a consequence of the high environmental priority. Results show that the effectiveness of water pricing for reducing irrigation demand is also scenario-dependent. Where regional food production is important, irrigation demand is relatively price-insensitive and abstraction controls will be most effective, whereas in a global market-drive future, irrigation demand is shown to be price-sensitive.

Agriculture: Disaster-Ready Corn

In the past 15 years, the number of droughts and other weather-related natural disasters worldwide has more than doubled, according to the international nonprofit Future Harvest. So it was welcome news when researchers at the University of California, Riverside, reported in the December 2004 Plant Journal what could be a way to improve the drought resistance of maize. Maize is now the most widely produced cereal in the world, having overtaken rice and wheat. Many areas where maize is grown, including parts of Africa, are vulnerable to drought. Ethylene, a compound produced by plants, is believed to help plants adapt to stress, but can also cause leaves to wither in response to dry conditions. Daniel Gallie and colleagues found that the leaves of reduced-ethylene plants remained green longer than normal plants, and that reducing a plant’s ethylene production postponed withering and maintained leaf function. Gallie and his colleagues identified transposons that had knocked out the enzyme that starts ethylene production in maize. Transposons are DNA elements that move from one position in the genome to another, knocking out the gene at the new position and replacing it. After screening thousands of plants, they found plants with mutant DNA affecting two of the three genes that make an enzyme needed for ethylene production. After confirming that the knockout mutants indeed produced less ethylene, they multiplied those plants and examined their growth in Riverside’s research fields. Not only did the mutant plants’ leaves stay green longer than normal plants, the plants’ leaves experienced higher-than-normal photosynthesis rates. It’s still unknown whether the mutation improves the plants’ cereal productivity as well as leaf production, and how reduction of ethylene affects other plant functions. Jerry Cohen, deputy division director for Molecular and Cellular Biosciences at the National Science Foundation, says that in maize, ethylene also encourages rooting and adaptation to flooding; simply reducing ethylene in maize, he says, “could end up with nice plants lying on the ground.” Still, he adds, this study opens many new possibilities for maize improvement. Mary Eubanks, a maize researcher at Duke University, notes that by providing better nutrition during drought, hardy maize would help maintain people’s immune systems and make them better able to resist infectious diseases. In the United States (the largest maize producer), hardier plants could reduce irrigation demand and consequent runoff. Irrigation represents more than half of the world’s freshwater demand, yet most of that is lost to evaporation, and runoff can pollute surface and groundwater with agricultural chemicals. Gallie sees another potential benefit. With climate change, he says, competition between urban and agricultural demands on scarce water resources is likely to intensify. Any crop that uses less water can help ease that conflict. Cohen concurs: “Efficient use of water is the dominant theme of twenty-first century agriculture.”

Potassium Nutrition and Moisture Stress Tolerance of Salvia

Elevated K fertilization during bedding plant production may reduce irrigation demand and moisture stress during marketing and landscape establishment. Lindhauer (1985) indicated increasing K fertilizer concentration reduced transpirational water loss and decreased the influence of moisture stress on gas exchange for sunflower. The objective of this study was to determine the influence of K nutrition level on gas exchange of salvia (Salvia splendens F. Sellow ‘Bonfire’) during the onset of moisture stress. Seed of salvia were sown on 11 Jan. 1988 and transplanted 14 days later into 500-ml plastic pots containing a 1 peat : 1 perlite (v/ v) medium amended with 1 kg of Micromax (Sierra Chemical Co., Milpitas, Calif.) and 3 kg dolomitic limestone/m. Plants were grown in a glasshouse under long-day conditions [night interruption from 2200 to 0200 HR using incandescent lights providing ≈4 μmol·s ·m photosynthetic photon flux (PPF) at the top of the plant canopies] to extend vegetative growth. Potassium was applied with each watering at 75, 300, or 600 mg K/liter from KCl. Each K solution also contained (in mg·liter) 200 N from NH4NO3 and 25 P from phosphoric acid. Solutions were applied at the rate of 250 ml at each watering to maintain constant root-zone concentrations of nutrients. Treatments were arranged in a randomized complete block design with eight single-plant (eight pots) replicates for each treatment. Plants were irrigated at 0545 HR and placed under supplemental lighting provided with 1000-W high-pressure sodium lamps. Levels of PPF ranged from 605 to 745 μmol·s ·m during gas exchange measurements. Net photosynthesis (Pn), transpiration (E), leaf conductance (gL), and internal CO2 concentration (CI) were obtained using the LI-COR Model 6200 portable photosynthesis system (LI-COR, Lincoln, Neb.). Mean gas analyzer leaf chamber relative humidity, temperature, and CO2 concentration during measurements were 38% ± 7% 27 ± 2C, and 360 ± 27 mg·liter, respectively. Mes-