Optimizing wheat productivity through integrated management of irrigation, nutrition, and organic amendments.

Enhancing wheat productivity by implementing a comprehensive approach that combines irrigation, nutrition, and organic amendments shows potential for collectively enhancing crop performance. This study examined the individual and combined effects of using irrigation systems (IS), foliar potassium bicarbonate (PBR) application, and compost application methods (CM) on nine traits related to the growth, physiology, and yield of the Giza-171 wheat cultivar. Analysis of variance revealed significant (P ≤ 0.05) main effects of IS, PBR, and CM on wheat growth, physiology, and yield traits over the two growing seasons of the study. Drip irrigation resulted in a 16% increase in plant height, leaf area index, crop growth rate, yield components, and grain yield compared to spray irrigation. Additionally, the application of foliar PBR at a concentration of 0.08 g/L boosted these parameters by up to 22% compared to the control. Furthermore, the application of compost using the role method resulted in enhanced wheat performance compared to the treatment including mix application. Importantly, the combined analysis revealed that the three-way interaction between the three factors had a significant effect (P ≤ 0.05) on all the studied traits, with drip irrigation at 0.08 g PBR rate and role compost application method (referred as Drip_0.08g_Role) resulting in the best performance across all traits, while sprinkle irrigation without PBR and conventional mixed compost method (referred as sprinkle_CK_Mix) produced the poorest results. This highlights the potential to synergistically improve wheat performance through optimized agronomic inputs.

Efficiency dynamics among onion growers in Maharashtra: a comparative analysis of drip irrigation adopters and non-adopters.

BACKGROUND: Onions are economically and nutritionally important vegetable crops. Despite advances in technology and acreage, Indian onion growers face challenges in realizing their full productivity potential. This study examines the technical efficiency of onion growers, the factors influencing it, and the constraints faced by those adopting drip irrigation in the Ghod river basin of western Maharashtra. A sample of 480 farmers including those practicing drip irrigation and those not practicing it, was selected from Junnar, Shirur, Parner, and Shrigonda blocks of the basin. The primary data was collected through semi-structured interviews. Analytical tools such as the Cobb-Douglas production function (represents technological relationship between multiple inputs and the resulting output), a single-stage stochastic frontier model, the Tobit model, and descriptive statistics were used to assess the technical efficiency of onion production at the farm level. RESULTS: According to the maximum likelihood estimates of the stochastic frontier analysis, drip adopters exhibited a mean technical efficiency of 92%, while for non-adopters it was 65%. It indicates that the use of drip irrigation technology is associated with higher technical efficiency. The association of technical efficiency and socio-economic characters of households showed that education, extension contacts, social participation, and use of information sources had a positive influence on technical efficiency, while family size had a negative influence on the drip irrigation adopters. For non-drip adopters, significant positive effects were observed for landholding, extension contact, and information source use. The major constraints faced by drip system adopters included a lack of knowledge about the proper operating techniques for drip systems and the cost of maintenance. CONCLUSION: The differences with inputs associated with two irrigation methods showed that the response of inputs to increase onion yield is greater for farmers who use drip irrigation than for farmers who do not, and are a result of the large differences in the technical efficiencies. These inefficiencies and other limitations following the introduction of drip irrigation, such as lack of knowledge about the proper operations, need to be addressed through tailored training for farmers and further interventions.

Conservation agriculture works as a catalyst for sustainable sodic soil reclamation and enhances crop productivity and input use efficiency: A scientific inquiry.

Soil sodicity is a growing concern for crop growth and development in arid and semi-arid regions of the world. Conservation agriculture (CA) provides an effective solution towards reclamation of degraded sodic lands and enhance the crop productivity. A field experiment was carried out to assess the sodic soil reclamation potential of CA based management practices including zero tillage, legume (mungbean; Mb) rotation, residue (+R) mulch, and subsurface drip irrigation (SDI) for three years under rice-wheat (RW) system. The system scenarios (Sc) comprised of multiple indicators to measure their impact on soil properties as well as system productivity, profitability, water and nitrogen use efficiency. The results indicated that soil pHs under Sc5-Sc8 (CA-based SDI scenarios) was significantly (p < 0.05) lowered by 2.16, 2.16 and 1.33% compare with mean of Sc1 and Sc2 (CT-based system; 9.10, 8.29 and 8.14) at all three soil layers (0-5, 5-15 and 15-30 cm), respectively. Similarly, the exchangeable sodium percentage (ESP) was lowered by 2.9, 11.2 and 14.9% under CA-based scenarios with residue management compared with CT-based system (mean of Sc1 and Sc2; 15.2, 17.2 and 28.6%) during the study. The concentration of extractable anions (COЗ2‾, HCOЗ‾, Cl‾) decreased notably whereas, soil organic carbon and soil solution cations (Na+, Ca2+, Mg2+) concentration were increased under CA based management SDI plots. In addition, CA with SDI scenarios (mean of Sc5-Sc8) proved to be more productive and water-efficient than CA-based flood irrigation (FI; mean of Sc3 and Sc4). Moreover, CA-based FI and SDI scenarios saved 29.5 and 60.7% irrigation water, and improved the partial factor productivity of nitrogen (PFPN) by 6.8 and 24.4%, respectively compared to CT-R (conventional tillage without residue) based Sc1. Therefore, CA practices can potentially reduce sodicity and improve soil chemical properties for profitable crop cultivation.

Generalizing routes of plant exposure to pesticides by plant uptake models to assess pesticide application efficiency.

Pesticide application techniques are critical not only for integrated pest management (IPM) but also for food and environmental safety. Assessing pesticide application efficiency on plants can help optimize IPM and reduce pesticide environmental impacts. With hundreds of pesticides registered for use in agriculture, this study proposed a modeling approach based on plant uptake models for generalizing routes of plant chemical exposures that can correspond to different types of pesticide application methods and evaluating their respective efficiency on plants. Three representative pesticide application methods (i.e., drip irrigation, foliar spray, and broadcast application) were selected for modeling simulations. The simulation results for three representative pesticides (i.e., halofenozide, pymetrozine, and paraquat) revealed that the soil-based transpiration exposure route facilitated the bioaccumulation of moderately lipophilic compounds in leaves and fruits. While the plant surface-based exposure route (i.e., leaf cuticle penetration) made it easier for highly lipophilic compounds to enter plants, moderately lipophilic pesticides (i.e., log KOW ∼ 2) were more soluble in phloem sap, which enhanced their subsequent transport within plant tissues. In general, moderately lipophilic pesticides had the highest simulated residue concentrations in plant tissues for the three specific application methods, indicating they had the highest application efficiency due to their enhanced uptake routes (via transpiration and surface penetration) and increased solubility in xylem and phloem saps. Compared to foliar spray and broadcast application, drip irrigation produced higher residue concentrations for a wide variety of pesticides, exhibiting the highest application efficiency for many pesticides, especially for moderately lipophilic compounds. Future research should incorporate plant growth stages, crop safety, pesticide formulations, and multiple application events into the modeling approach for understanding pesticide application efficiency evaluation.

Influence of microclimate control on the growth of asparagus under greenhouse in tropical climates.

High temperatures have become common in cities in Taiwan, and this phenomenon has spread to surrounding agricultural areas. Tainan, a city located in a tropical climate zone with agriculture as its primary development industry, is one of the cities considerably affected by the high temperature. High temperatures can reduce crop yields and even cause plant death, especially for vulnerable high-value crops, which are severely to microclimate conditions. Asparagus is a high-value crop that has long been cultivated in the Jiangjun District of Tainan. Recently, asparagus has been planted in greenhouses to protect against pests and natural disasters. However, the greenhouses can overheat. To identify the optimal growth environment for asparagus, this study applies vertical monitoring to record the temperature in the greenhouse and the soil moisture content of a control (canal irrigation) and an experimental (drip irrigation) group. When the surface layer of the soil exceeds 33°C, the tender stems of asparagus bloom readily, reducing its commercial value. Therefore, drip irrigation was conducted with cool water (26°C) to reduce soil temperature in summer and warm water (28°C) to increase soil temperature in winter. The study also recorded the growth of asparagus using daily yields measured by farmers during weighing and packing to understand the benefits of controlling the greenhouse microclimate. This study reports a correlation of 0.85 between asparagus yield and temperature and a correlation of 0.86 between asparagus yield and soil moisture content. The use of a drip irrigation system with a water temperature adjustment function not only saves up to 50% of water but also resulted in an average yield increase of 10% through maintaining stable soil moisture content and temperature. Therefore, the findings of this study can be applied to asparagus yields affected by high temperature and can solve the problems of poor quality in summer and low yield in winter.

Flushing control strategies to improve the stability of a biogas slurry drip irrigation system: Behavioral characteristics and mechanisms.

Biogas slurry drip irrigation can mitigate environmental pollution and reduce the use of chemical fertilizers to enable sustainable development. However, the stability of the biogas slurry drip irrigation system (BSDIS) is disrupted by emitter clogging; hence, it is essential to explore the flushing control strategy of BSDIS. By means of combining actual measurement and simulation, this study investigates the BSDIS stability based on the three technical parameters of the flushing control strategy. Appropriate flushing control strategies can improve system stability and cause spatial differences on the drip irrigation tape. Under various flushing control strategies, the system stability primarily undergoes delays, sensitivity, and ineffectiveness of flushing with time. Compared with the without flushing and emitter outlet downward-oriented treatment, the optimal flushing combination (the high frequency flushing + emitter outlet upward-oriented treatment) reduces the emitter clogging content by approximately 70.97% and increases system stability by 189.1%. In the internal hydrodynamics, the laying direction of emitters does not change the movement characteristics of water flow, although the clogging particles do not completely follow the water flow, with some particles settling owing to gravity, thereby clotting the emitters. When clogging occurs, the increase in flushing speed is conducive to the increase in turbulent kinetic energy on the inlet surface of the emitter, which facilitate the flushing of clogged substances. This study proposes optimal flushing strategy parameters along with a new management mode for the waste liquid represented by biogas slurry.

The use of alternative irrigation and cropping systems in forage production may alleviate the water scarcity in semi-arid regions.

BACKGROUND: 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. RESULTS: 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. CONCLUSIONS: 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.

Timing and water temperature of drip irrigation regulate cotton growth and yield under film mulching in arid areas of Xinjiang.

BACKGROUND: Cotton (Gossypium hirsutum L.) is the fiber crop most widely cultivated globally and one of the most important commercial crops in China, irrigation is closely related to the growth of cotton. A water temperature for irrigation that is too low or too high inhibits cotton growth. Poor irrigation timing results in water and nutrient deficiencies that reduce cotton yield. Therefore, it is necessary to determine the appropriate irrigation timing and water temperature. METHOD: We conducted an experiment in an arid region of north-western China to assess the effects of irrigation timing and water temperature on soil temperature and the photosynthetic characteristics, biomass, total nitrogen (N), and seed cotton yield. Two irrigation times (daytime and nighttime) and four water temperatures (15, 20, 25, and 30 °C) were combined into eight treatments. RESULTS: Our results showed that water warming and nighttime irrigation improved the photosynthesis, biomass, N concentration (the proportion of total N weight in the plant biomass, in g kg-1 ), N content (the mass of total N, in g plant-1 ), and cotton yield. The optimal water temperature range for photosynthesis was 25.7-28.7 °C. Water warming also boosted the biomass allocation to the stem and increased the N allocation to the stem and leaf. Nighttime irrigation enhanced these phenomena. Water warming also increased the number of bolls per plant but reduced the single boll weight, increasing the seed cotton yield by 5.88-11.46%. At the same water temperature, irrigation during the night increased the number of bolls per plant and the single boll weight, improving the seed cotton yield by 2.95-4.31%. Among them, NI25 (nighttime irrigation with 25 °C water temperature) increased the yield by 14.13-14.90% compared with CK (daytime irrigation with 15 °C water temperature), which offers the best combination for increasing the yield. CONCLUSION: Our study clarifies the optimal irrigation timing and water temperature for cotton production under drip irrigation with film mulching, providing valuable information for improving the cotton yield in arid areas with temperate continental climate. © 2023 Society of Chemical Industry.

Long-term numerical modeling of nitrate leaching into groundwater under surface drip irrigation of corn.

Proper management of fertigation is necessary to deal with the harmful impacts of fertilizers. This research aimed to investigate the nitrate leaching rate into groundwater in different fertigation management under the climate change impact in drip irrigation of corn. For this purpose, HYDRUS-2D was calibrated by performing field experiments. Plant water requirement and rainfall were projected until 2050 using LARS-WG6 under the RCP85 scenario. Then, nitrate leaching up to groundwater at the depth of 5 m was simulated in the growing season of corn and the like until 2050 in three fertigation scenarios, including S1 (three regional fertigation splits with irrigation efficiency of 85%), S2 (weekly fertigation with irrigation efficiency of 85%), and S3 (optimum fertigation with irrigation efficiency of 100%). Finally, the annual nitrate leaching rate to groundwater and leached amount were compared in the studied scenarios. The results demonstrated that nitrate penetrated to the depth of 117 and 105 cm at the end of the first year in S1 and S2 scenarios, respectively. In these scenarios, nitrate will reach groundwater in 2031, but nitrate concentrations will not be the same. In the S3 scenario, the nitrate will reach a depth of 180 cm by 2050. Total leached nitrate to groundwater up to 2050 will be 1740, 1200, and zero kg/ha in S1, S2, and S3 scenarios, respectively. Based on the approach of this study, the vulnerability of groundwater to nitrate contamination in different agricultural areas can be evaluated, and appropriate strategies with minimum environmental impacts of fertilizer abuse can be selected accordingly.

Investigation of Multi-Frequency SAR Data to Retrieve the Soil Moisture within a Drip Irrigation Context Using Modified Water Cloud Model.

The objective of this paper was to estimate soil moisture in pepper crops with drip irrigation in a semi-arid area in the center of Tunisia using synthetic aperture radar (SAR) data. Within this context, the sensitivity of L-band (ALOS-2) in horizontal-horizontal (HH) and horizontal-vertical (HV) polarizations and C-band (Sentinel-1) data in vertical-vertical (VV) and vertical-horizontal (VH) polarizations is examined as a function of soil moisture and vegetation properties using statistical correlations. SAR signals scattered by pepper-covered fields are simulated with a modified version of the water cloud model using L-HH and C-VV data. In spatially heterogeneous soil moisture cases, the total backscattering is the sum of the bare soil contribution weighted by the proportion of bare soil (one-cover fraction) and the vegetation fraction cover contribution. The vegetation fraction contribution is calculated as the volume scattering contribution of the vegetation and underlying soil components attenuated by the vegetation cover. The underlying soil is divided into irrigated and non-irrigated parts owing to the presence of drip irrigation, thus generating different levels of moisture underneath vegetation. Based on signal sensitivity results, the potential of L-HH data to retrieve soil moisture is demonstrated. L-HV data exhibit a higher potential to retrieve vegetation properties regarding a lower potential for soil moisture estimation. After calibration and validation of the proposed model, various simulations are performed to assess the model behavior patterns under different conditions of soil moisture and pepper biophysical properties. The results highlight the potential of the proposed model to simulate a radar signal over heterogeneous soil moisture fields using L-HH and C-VV data.

Residue and distribution of drip irrigation and spray application of two diamide pesticides in corn and dietary risk assessment for different consumer groups.

BACKGROUND: As the use of diamide insecticides on corn continues to increase, there is growing concern about their residue levels on corn and dietary risks to populations. In this study, the distribution, dispersion and transfer efficiency of two diamide insecticides (tetrachlorantraniliprole (TCAP) and cyantraniliprole (CNAP)) in different parts of corn and soil were investigated in a 1-year field trial in Guangzhou and Lanzhou using two different application methods - spray and drip irrigation, respectively - and the dietary risk of the insecticides to different consumer populations was assessed under the two application methods. RESULTS: The results showed that drip irrigation had a longer persistence period than spraying, and there was a hysteresis in the absorption distribution of the agent in different parts of corn, which was gradually transferred to the leaves after absorption from the roots. The average TE1 (transfer efficiency) and TE2 were 0.230-0.261 and 1.749-1.851 for TCAP and 0.168-0.187 and 2.363-2.815 for CNAP, respectively. At corn harvest, both TCAP and CNAP were below detectable levels in soil and corn. For different consumer populations, hazard quotients ranged from 0.001 to 0.066 for TCAP and from 0.003 to 0.568 for CNAP - both well below 100%. CONCLUSION: This study indicates that TCAP and CNAP applied by spray or drip irrigation are safe for long-term risk of human intake and also provides guidance for the use of both insecticides in agricultural production to control corn pests, especially in arid and semi-arid areas. © 2022 Society of Chemical Industry.

Emitter clogging characteristics under reclaimed wastewater drip irrigation: a meta-analysis.

BACKGROUND: Although reclaimed wastewater drip irrigation (RWDI) is an effective technology for alleviating agricultural crop water stress and protecting the environment, the reclaimed wastewater (RW) may cause emitter clogging. Discharge ratio variation (Dra) and coefficient of uniformity (CU) play a key role in exploring the clogging degree of the emitter. Therefore, a meta-analysis was conducted to identify optimal management methods with an acceptable Dra and CU under RWDI. RESULTS: The results indicate that the higher the concentration of various substances in RW, the higher is the risk of the emitter clogging. Suitable concentrations of iron (Fe), manganese (Mn), total suspended solids (TSS), chemical oxygen demand (COD), water hardness and calcium ions (Ca2+ ) in RW were determined to be 0-0.2, 0-0.02, 0-50, 20-30, 200-250 and 0-40 mg L-1 , respectively. Pressure-compensating emitters with relatively high discharge (>2 L h-1 ) could prevent clogging in RWDI systems. CONCLUSION: Based on the data analysis, a cumulative RWDI operation time of 375 h was determined as the most suitable time for lateral flushing to prevent clogging. This study identifies the conditions under which an increase in the service life of RWDI systems can be achieved. © 2022 Society of Chemical Industry.

A global meta-analysis of nitrous oxide emission from drip-irrigated cropping system.

Drip irrigation is a useful practice to enhance water and fertilizer nitrogen (N) use efficiency. However, the use of drip irrigation to mitigate nitrous oxide (N2 O) emissions in agricultural systems globally is uncertain. Here, we performed a global meta-analysis of 485 field measurements of N2 O emissions from 74 peer-reviewed publications prior to March 2021, to quantify the fertilizer-induced N2 O emission factor (EF) of drip irrigation and examine the influencing factors of climate, crop, soil properties, and source and rate of fertilizer N application. The results showed that drip irrigation reduced (p < 0.05) N2 O emissions by 32% and 46% compared to furrow and sprinkler irrigation systems, respectively. The overall average EF with drip irrigation was 0.35%, being two-thirds lower than the IPCC Tier I default value of 1% (kg N2 O-N/kg added fertilizer N). The EF was not significantly affected by climate, crop, soil texture, soil organic carbon content, and pH. The EF was also not significantly (p > 0.05) affected by synthetic N fertilizer source despite a lower numerical value with enhanced efficiency than conventional fertilizers. The EF increased significantly (p < 0.001) with N addition rate in a binomial distribution. Using the IPCC default EF overestimated N2 O emissions inventories for drip-irrigated cropping systems by 7614 and 13,091 Mg per year for China and the globe, respectively. These results indicate that drip irrigation should be recommended as an essential N2 O mitigation strategy for irrigated crop production.

Mitigating global warming potential while coordinating economic benefits by optimizing irrigation managements in maize production.

China is the second largest irrigated country in the world. Increasing irrigation intensity costs more water and energy, and produces more greenhouse gas (GHG). In the present study, the responses of maize economic and environmental benefits to different irrigation managements were analyzed in a 2-year field study. A purposely designed tube-study was conducted to explore mechanism underlying effects of irrigation managements in detail. Three treatments, rainfed (RF), flood irrigation (FI), and drip irrigation (DI) were included in the field. Five treatments, no irrigation, flood irrigation, irrigation in 0-30, 30-60, and 0-90 cm depth were conducted in the tube study. Compared to RF, grain yields of FI and DI significantly increased by 22.1 % and 35.7 %, respectively, the net ecosystem economic budget significantly increased by 34.2 % and 35.6 %, and carbon footprint decreased by 7.0 % and 12.7 % in the field study. The irrigation treatments in the tube study increased the global warming potential by 12.0-32.8 % and grain yield by 44.5-203.9 %, and reduced GHG intensity by 24.3-57.4 %, compared with no irrigation treatment. Water content at the top soil layer had the greatest impact on GHG emissions. In conclusion, the differences in grain yield and GHG emissions among irrigation managements are mainly due to the soil water content in space and time. Drip irrigation decreases GHG intensity by producing more grain yield due to the optimized soil water distribution in the root zone. Irrigation management with appropriate amount and frequency can increase economic benefit and reduce environmental cost in maize production.

Productivity and heavy metal pollution management in a silage maize field with reduced recycled wastewater applications with different irrigation methods.

Using wastewaters in irrigated agriculture can cause heavy metal accumulation as well as salinity in soil. A practical way of minimizing accumulation in soil is to use irrigation techniques that require less water and consequently introduce less heavy metals into the feeding chain in silage maize cultivation with wastewater irrigation. The objective of this study is to address this issue. A factorial field experiment was carried out for two years in a completely randomized design with three replicates. Experimental plots were irrigated with three different irrigation methods (subsurface and surface drip, and furrow) applying three different levels (full irrigation and 33 and 67% deficit irrigations) of recycled wastewater and freshwater. The results showed that soil heavy metal contents, salinity, macro nutrients, organic matter, cation exchange capacity, porosity and wet aggregate stability were significantly higher in full irrigation with wastewater, while pH, carbonates, bulk and particle densities were significantly lower. Drip methods reduced salinity and heavy metal contents significantly. Heavy metal pollution indexes also indicated that drip methods are more effective in reducing metal pollution in soil. However, considerable accumulations of Cd and Ni were found with all methods while deficit irrigation decreased accumulations. The highest cation exchange capacity and K2O contents and the lowest exchangeable sodium percentage were determined with the subsurface drip method. The subsurface drip method saved 20.7 and 49% more irrigation water than the surface drip and furrow methods under fully irrigated conditions. Therefore, it can be concluded that using the subsurface drip method with recycled wastewater can be used in silage maize cultivation because soil productivity and water savings increased while metal pollution and salinity in soil decreased. Moreover, using 33% less wastewater can be a useful practice to decrease Cd and Ni accumulation.

A 2-year study of the impact of reduced nitrogen application combined with double inhibitors on soil nitrogen transformation and wheat productivity under drip irrigation.

BACKGROUND: Nitrification inhibitors (NIs) and urease inhibitors (UIs) can decrease the risk of nitrogen (N) loss and extend N uptake by plants. However, there are few case studies about reduced N application combined with double inhibitors (DIs, NI plus UI), especially under drip irrigation systems. A 2-year field experiment was therefore conducted to explore the effect of 80% N application rate combined with NI or DIs on soil N transformation, wheat productivity and N use efficiency (NUE) in a drip-irrigated field. The four treatments included a no-fertilizer control, 100% urea, 80% urea + NI (nitrapyrin) and 80% urea + DIs (nitrapyrin and N-(n-butyl) thiophosphorictriamide (NBPT)). RESULTS: Our results showed that the 80% urea + DIs treatment significantly increased the ratio of NH4 + to NO3 - and N content (urea-N, NH4 + -N and NO3 - -N) in soil at 0-20 cm depth (P < 0.05) at the heading stage and the filling stage of wheat in both 2013 and 2014, relative to the 100% urea treatment. A total of 80% urea + NI treatment decreased wheat N uptake and wheat productivity (plant biomass and yield) compared to 100% urea treatments (P < 0.05). However, application of 80% urea combined with DIs achieved equivalent wheat productivity with 100% urea treatment. Moreover, the greatest NUE (43.6%) was recorded with the application of DIs. CONCLUSIONS: Cutting the N application rate by 20% combined with NBPT and nitrapyrin could provide a sustainable fertilization strategy for wheat production under drip irrigation. © 2020 Society of Chemical Industry.

Can drip irrigation under mulch be replaced with shallow-buried drip irrigation in spring maize production systems in semiarid areas of northern China?

BACKGROUND: In recent years, shallow-buried drip irrigation in spring maize production has gradually replaced drip irrigation under plastic films and has become a common irrigation method in semiarid areas of northern China. RESULT: Two years of field experiments were carried out in the semiarid area of western Jilin province to compare the two drip irrigation methods in the spring maize production system. The treatments included MW1 (drip irrigation under mulch + moderate irrigation amount), MW2 (drip irrigation under mulch + high irrigation amount), SM1 (shallow-buried drip irrigation + moderate irrigation amount), and SM2 (shallow-buried drip irrigation + high irrigation amount). The maize yields were significantly higher under mulch than under shallow-buried drip irrigation, but there was no interaction between mulch and the irrigation amount. Drip irrigation under mulch greatly improved spring maize N, P and K uptake compared with that under shallow-buried drip irrigation. The agronomic-use efficiency, recovery-use efficiency, and partial factor productivity were ranked in the order of MW2 > MW1 > SW2 > SW1. The water-use efficiency of drip irrigation under mulch was 7.44% and 6.82% higher than that of shallow-buried drip irrigation under the moderate and high irrigation levels, respectively. However, considering the costs of the plastic mulch, there was no significant (P < 0.05) difference in economic benefits between the SW and MW treatments. CONCLUSION: Drip irrigation under plastic film provides greater advantages for production, but shallow-buried drip irrigation may be a suitable method for farmers until fertigation technology is further optimized and the problem of plastic film pollution is solved. © 2020 Society of Chemical Industry.

Controlled comparisons between soil and hydroponic systems reveal increased water use efficiency and higher lycopene and ß-carotene contents in hydroponically grown tomatoes.

There are many different types of systems used to grow food that are distinguished by ideology or the technology used. It is often difficult to directly compare yield and quality in different growth systems due to the complicated interactions between genotype, physiology and environment. Many published comparisons do not identify and acknowledge confounding factors. However, there is urgency to undertake controlled comparisons to identify the most efficient and effective food production systems, because the world faces considerable challenges to food supply with population rise, ongoing environmental degradation and the threat of climatic change. Here we compared soil with two hydroponic growth systems, drip irrigation and deep-water culture (DWC). It is often claimed that such systems differ in water use, yield and crop quality; however, such comparisons are often confounded by assessing plant and system parameters in different growth environments or where factors that are difficult to standardise between systems, such as nutrient status, are not controlled. We grew tomato (Solanum lycopersicum L.) in the three growth systems in two replicated experiments, in either a polytunnel or glasshouse. We controlled and monitored water use and nutrient levels across all systems as different fertilizer applications can influence the nutritional values of produce. Plants in the two hydroponic systems transpired less water and were more water-efficient with a lower product water use than plants grown in soil. Fruit yield was similar and total soluble solids and sugar levels were not significantly different between the three growing systems. However, levels of lycopene and ß-carotene were either similar or significantly higher in DWC compared to growth systems using soil or drip irrigation. Our results identify hydroponic systems as more water use efficient with DWC also capable of producing higher quality produce.

Using phosphate fertilizer to reduce emitter clogging of drip fertigation systems with high salinity water.

Phosphorous (P) fertigation with high salinity water (HSW) drip irrigation would be an effective measure to relieve soil and water pollution caused by the excessive application of P fertilizer, and achieve synergistic saving of both limited fresh water and non-renewable P resources. However, the emitter clogging issues of drip fertigation systems seriously restricts the utilization of this technology. This study proposes an approach to reduce emitter clogging in HSW drip fertigation systems by choosing the appropriate type and concentration of P fertilizer. The effects of two new types of P fertilizers (ammonium polyphosphate, APP; urea phosphate, UP), and a traditional P fertilizer (monopotassium phosphate, MKP), were assessed at three fertilization concentrations (0, 0.15, and 0.30 g/L) on the clogging behavior of four types flat emitters. The results indicated that the application of MKP aggravated the clogging of emitters in comparison with non-fertilization. While the addition of two new types of P fertilizers (APP and UP) effectively alleviated emitters clogging (the irrigation uniformity of systems increased by 26.2%-74.6%) by inhibiting the formation of carbonate, although precipitation of phosphate, silicate, and quartz increased. Moreover, under the equal application amount of P fertilizer, UP and APP were more effective in relieving clogged when applied at a low-concentration with long-term running and high-concentration with short-term running mode. The results could pave a way for reducing the pollution in agricultural production and conserving freshwater and non-renewable P resources.

Plastic film mulching stimulates brace root emergence and soil nutrient absorption of maize in an arid environment.

BACKGROUND: Root-shoot ratio plays an important role in mulching effects on increases in maize kernel dry weight and grain yield. RESULTS: We examined the effects of plastic film mulching with fertigation on soil nitrate, soil Olsen-P, aboveground and belowground growth, grain filling, and yield of maize. The 2-year research was conducted in a field with a subsoil sand layer (FSS) and in a field without a subsoil sand layer (FNS) in the Hetao Irrigation District, northwest China. Treatments included two levels of plastic film mulching (FM, fully mulched; PM, partially mulched with a cover ratio of 60%), and a non-mulched (NM) control. Mulching methods significantly increased soil NO3 -N concentrations (SNCs) in the main root zone in FSS, but not in FNS. Mulching significantly increased root length density in the 0-40 cm soil layer. Mulching increased brace roots emergence by 20.2% under full, and by 9.9% under partial mulching, accelerating soil phosphorus use in the surface soil layer. Mulching increased grain yield in spring maize via enhancing base stem diameter, leaf area, and relative chlorophyll content, decreased the ratio of surface root area to leaf area, and improved kernel dry weight increase. CONCLUSIONS: A high proportion of base fertilizer to total fertilizer input resulted in nutrient deficiency during reproductive stage in fertigated maize, therefore, applying a portion of base fertilizer after the maize elongation stage is recommended for a further yield increase of mulched fertigated maize. © 2019 Society of Chemical Industry.