Reduce Soil Water Evaporation Research Articles

Effects of Different Mulch Types on Farmland Soil Moisture in an Artificial Oasis Area

Different types of mulch are often used in agricultural production to enhance soil moisture and improve crop yields. The question of which mulch provides superior water retention in arid regions, where water resources are scarce, is a major concern for agricultural production. We conducted observations and studies at a typical irrigated experimental station in an arid zone with four types of mulch, including liquid mulch (LM), biodegradable mulch (BM), ordinary black mulch (OBM), and ordinary white mulch (OWM), and plots with no mulch. Samples were collected and analyzed at 1, 3, 5, and 7 days after each rainfall or irrigation to obtain soil moisture changes and to analyze the effect of different mulches on soil moisture retention. The results showed that mulch cover was effective in retaining soil moisture compared to plots without mulch cover. Specifically, soil moisture was highest in the farmland with OWM during the observation period. OWM, OBM, and BM were all effective in reducing soil water evaporation and maintaining soil moisture. LM and BM were capable of utilizing rainfall to recharge soil water in a superior way, and polyethylene mulches (OBM and OWM) had a significant barrier impact on rainfall.

Effects of Bio-Organic Fertilizer on Soil Infiltration, Water Distribution, and Leaching Loss under Muddy Water Irrigation Conditions

This study analyzes the soil water infiltration characteristics under muddy water irrigation and bio-organic fertilizer conditions in the current context of muddy water irrigation rarely being used in agricultural production and in combination with the problems of water resource shortages and low soil fertility in arid and semi-arid regions. An indoor one-dimensional soil column infiltration device was used for studying the effects of four muddy water sediment concentration levels (ρ0: 0; ρ1: 4%; ρ2: 8%; ρ3: 12%) and four bio-organic fertilizer levels (FO0: 0; FO1: 2250 kg·hm−2; FO2: 4500 kg·hm−2; sFO3: 6750 kg·hm−2) on soil water infiltration, evaporation characteristics, and leaching loss. The results demonstrated that a higher muddy water sediment concentration and fertilization level resulted in a smaller wetting front distance and cumulative infiltration amount within the same time, but the infiltration reduction rate (η) gradually increased. The three infiltration models (Kostiakov, Philip, and Horton) were fitted, and it was discovered that all three had good fitting results (R2 > 0.8), with the Kostiakov model displaying the best fit and the Horton model exhibiting the worst fit. The cumulative evaporation amount and evaporation time in muddy water irrigation and fertilization conditions was consistent with the Black and Rose evaporation models (R2 > 0.9), the Black model was proved to be higher than the Rose model. In comparison to ρ0, muddy water irrigation increased conductivity and total dissolved solids (TDS) in the leaching solution, but it reduced cumulative evaporation, soil moisture content, the uniformity coefficient of soil water distribution, and leaching solution volume. Compared with FO0, the application of bio-organic fertilizer increased soil water content and reduced soil water evaporation while also reducing the leaching solution volume, conductivity, and TDS in the leaching solution. The results of this research can provide scientific reference for the efficient utilization of muddy water irrigation and the rational application of bio-organic fertilizer.

Effect and Application of Different Amendments on Salinized Soil Remediation

At present, China's saline-alkali soil area is very large. In the saline-alkali soil, the salinity will affect the growth of plants in the severe areas, so the plants cannot survive. How to maintain soil quality and prevent soil salt from being high has become an important research goal of soil improvement. Soil amendments can combine many small soil particles together to form large water stable aggregates. And it is widely used to prevent soil erosion, reduce soil water evaporation or excessive evaporation, save the amount of irrigation and promote the healthy growth of plants. This study through the use of homemade iron han ecological amendments, phosphogypsum, garden waste decay secondary materials, five materials mixed polyacrylamide and microbial amendments, combined with the water salt engineering comparison experiment, the whole experiment for three, respectively is composite amendments and water salt engineering comprehensive improvement measures (TG1, TG2), the traditional composite amendments (G 1, G 2) and tai tian shallow water conservancy salt project (T) single measures. In the above experiments, the best effects are TG 1 (comprehensive improvement measures of Tiehan ecological amendments) and TG 2 (comprehensive improvement measures of Heka amendments). Although the amount of reagent applied is different, the treatment effect is very good. The results show that different improvement measures significantly reduced the salt content and reduced the PH value of soil, and improved the soil nutrients. This measurement data provides a certain theoretical basis for the repair and study of salinized soil. It also shows that soil amendments have obvious guidance for the application of salinized soil.

Assessment of agricultural adaptations to climate change from a water-energy-food nexus perspective

Adapting agriculture to climate change without deteriorating natural resources (e.g., water and energy) is critical to sustainable development. In this paper, we first comprehensively evaluate six agricultural adaptations in response to climate change (2021–2050) through the lens of the water-energy-food (WEF) nexus in Saskatchewan, Canada, using a previously developed nexus model—WEF-Sask. The adaptations involve agronomic measures (early planting date, reducing soil evaporation, irrigation expansion), genetic improvement (cultivars with larger growing degree days (GDD) requirement), and combinations of individual adaptations. The results show that the selected adaptations compensate for crop yield losses (wheat, canola, pea), caused by climate change, to various extents. However, from a nexus perspective, there are mixed effects on water productivity (WP), total agricultural water (green and blue) use, energy consumption for irrigation, and hydropower generation. Individual adaptations such as early planting date and increased GDD requirement compensate for yield losses in both rainfed (0–60 %) and irrigated (18–100 %) conditions with extra use of green water (5–7 %), blue water (2–14 %), and energy for irrigation (2–14 %). Reducing soil water evaporation benefits the overall WEF nexus by compensating for rainfed yield losses (25–82 %) with less use of blue water and energy consumption for irrigation. The combination of the above three adaptations has the potential to sustain agricultural production in water-scarce regions. If irrigation expansion is also included, the combined adaptation almost fully offsets agricultural production losses from climate change but significantly increases blue water use (143–174 %) and energy consumption for irrigation while reducing hydropower production (3 %). This study provides an approach to comprehensively evaluating agricultural adaptation strategies, in response to climate change, and insights to inform decision-makers.

Technical feasibility of using a geotextile waste material as an alternative to agrofilm for mulching in lettuce

ABSTRACT In semiarid regions, water deficit can be a problem affecting agricultural production. Agrofilm mulches can be used to reduce soil water evaporation as well as to control weeds. The SoilTain DW® geotextile blanket, which is a solid waste material generated in water treatment plants, has the potential to be used for mulching in agriculture. The aim of this study was to evaluate the technical feasibility of using this geotextile waste material as an alternative to different agrofilms for mulching in lettuce under the semiarid conditions of the state of Alagoas, Brazil. Four experiments were carried out in 2020–2021, each with four mulching treatments (white and black polyethylene, geotextile blanket, uncovered soil). Soil surface temperature, plant density, weeds and biometric parameters of the lettuce were assessed and evaluated by univariate and multivariate statistical analyses. Significant treatments × experimental period interactions for all lettuce parameters were observed, except for root biomass. Experiment 2 (winter) presented the most favourable environmental conditions for plant development (mild temperatures) and resulted in an average yield of 25.0 Mg ha−1. In Experiment 1 (autumn/winter), high temperatures (47.9°C) under the black polyethylene reduced plant density (96,800 plants ha−1), though leaf length (16.2 cm) and yield (13.1 Mg ha−1) were not significantly affected. The two canonical variables explained 97.7% of the total variation, forming three similarity groups by Tocher method. All mulches effectively controlled the weeds. Application of the geotextile blanket was concluded to be technically feasible, but it was not recommended for use in the summer when temperatures are high.

Effect of Organic Mulch and Water Supply on Yield and Profitability in Black Nightshade (Solanum Scabrum Mill.) in West Cameroon

Water shortage and increased soil water evaporation are among challenges facing farmers in tropical regions subjected to prevailing climate change. Combinations of agricultural practices expected to improve yields of cultivated crops such as mulching has been described as a method to improve soil water storage and yields of cultivated crops including black nightshade. Unfortunately, up to date, few research works have addressed the yields and profitability of black nightshade. Combinations of rate of water, frequency of irrigation, mulch rate were tested during the 2021 and 2022 off-seasons for large-scale and cost-effective production of black nightshade, a staple food crop. A total of 18 triptych combinations of three irrigation volumes (Vn), three irrigation frequencies (Fn) and two mulch rates (Mn) were tested. Results showed that the best 5 yielding combinations (mean: 42.08 t/ha) represented 124% of the trial mean (33.80 t/ha) independently of the cropping year. However, combination V1F3M10 i.e. applying an average of 5.8 mm/day of water every 3 days on 10 t/ha-mulch plots led to the highest yield (47.16 t/ha) and profit (304.60%). Therefore, the combination V1F3M10 should be adopted for off-season production of black nightshade on Oxisol from West-Cameroon. Soil mulching at 10 t/ha promoted water saving by 402.3 mm and probably reduced soil water evaporation, weeds control, and improved water use efficiency.

No-tillage with straw mulching improved grain yield by reducing soil water evaporation in the fallow period: A 12-year study on the Loess Plateau

No-tillage with straw mulching (NTS) during the fallow period is an effective measure for storing precipitation and reducing soil water evaporation on the Loess Plateau of China. However, the duration of this effect of NTS during the fallow period in different cropping systems and different precipitation types is unclear. Therefore, a 12-year field experiment of two tillage methods (NTS; and conventional tillage, CT), in three cropping systems (winter wheat monoculture, WW; spring maize monoculture, MM; and winter wheat-spring maize rotation, WM) were conducted to evaluate the effect of NTS on grain yield, precipitation storage, soil water status, soil evaporation rate and cumulative soil evaporation during the fallow period in different precipitation types. Additionally, the duration for which NTS reduced soil evaporation was calculated using the linear-platform model. Our results showed that compared to CT, NTS increased precipitation storage by 35.3, 47.1 and 53.5 mm under WW, by 31.5, 31.5 and 40.4 mm under MM and by 53.2, 30.2 and 50.3 mm under WM in the wet, normal and dry fallow periods, respectively, at depths of 0–200 cm. As a result, the soil water storage at sowing was higher under NTS than that under CT. The linear-platform model showed that NTS was effective in reducing soil water evaporation for 86, 95 and 126 days under WW, 87, 81 and 110 days under MM, and 95, 104 and 121 days under WM in wet, normal and dry fallow periods, respectively. Additionally, we found that there was a large amount of cumulative soil water evaporation after the abovementioned durations in MM and WM. The path analysis indicated that NTS improved grain yields indirectly by reducing cumulative soil evaporation and increasing the soil water status at the sowing stage. Capturing precipitation when the fallow period is > 125 days may further improve yield.

Improvement on pest resistance of sprayable mulch films by fully utilizing garlic residues

Nutrient-rich liquid mulch films containing significant amounts of natural biomass inevitably attract pests, which hinder healthy crop development, despite the advantages of such mulch films in terms of degradability and low cost. To improve the pest resistance of mulch films derived from kitchen waste, we combined garlic residues, kitchen waste, and acrylic monomers to prepare sprayable garlic residue-acrylate liquid mulch films via emulsion polymerization. Garlic residues were fully utilized during the preparation process. The effects of the garlic residue dosage on the viscosity, sprayability, and wicking properties of the emulsions were, as well as the mechanics, water retention, and heat preservation of the garlic residue-acrylate films were studied. Microscopic, spectroscopic, and thermal analysis techniques were employed to characterize and monitor the biodegradability of the optimized garlic residue-acrylate films. The experimental results indicated that the film comprising a 3:7 wt ratio of garlic residues to acrylic monomers exhibited the best overall performance. The prepared garlic residue-acrylate mulch films effectively reduced soil water evaporation (by 2.1–12.3%) and increased soil temperature (by 1.26–3.75%). The optimized garlic residue-acrylate mulch film reached a biodegradation rate of 74.6% and increased the germination rate of pakchoi seeds by 20% relative to bare soil. Meanwhile, it reduced the degree of damage to pakchoi leaves by 11% and the survival rate of Plutella xylostella pests by 30% compared with the nutrient-rich film without garlic residues. The experimental results presented herein demonstrate that the full utilization of garlic residues can improve the performance of sprayable kitchen waste-based mulch films for agricultural applications.

Is Harvesting Cover Crops for Hay Profitable When Planting Corn and Soybean in Tennessee?

Winter cover crops can improve the soil’s moisture-holding capacity, reduce soil water evaporation, and mitigate water-induced soil erosion; however, economic studies show mixed results on cover crop impacts on profits. One way to potentially increase the profits from planting cover crops is to harvest the cover crop for hay. The objective of this study was to determine the profitability of planting and harvesting cover crops when planting corn (Zea mays) or soybean (Glycine max (L.) Merr.) as a cash crop. We determined the difference in net returns among 15 cover crop species when planted before corn and soybeans. We then calculated the breakeven hay price if the cover crop was harvested. Data were collected from an experiment in Tennessee, from 2017 to 2019, at two locations. There was no difference in net returns across cover crop treatments for both corn and soybeans, thus indicating that planting a cover crop does not reduce profits. The breakeven prices for harvesting cover crops suggest that this system would not likely be profitable for corn but might be profitable if planting soybeans, depending on labor availability and local demand for hay.

A new method for the treatment of kitchen waste: Converting it into agronomic sprayable mulch film

This report describes a new method for converting kitchen waste (KW) with high water content into mulch films that can be applied in agricultural production. Specifically, the KW was emulsion polymerized with acrylic monomers (in various proportions) to obtain a series of sprayable bio-based KW-acrylate mulch films. The films’ properties and performances were evaluated, and the experimental results showed that the KW-acrylate mulch films exhibited excellent sprayability, membrane formation, and mechanical properties, which allowed them to effectively reduce soil water evaporation (by 13–50%) and increase soil temperature (by 1.9–6.7%). Compared with bare soil, the soil treated with the optimized KW-acrylate mulch film increased the germination rate of rapeseeds by 20% and the yield of Chenopodium album by 0.7 times; the mulch film biodegradation then reached 70% after 100 days.

Plant residue mulch increases measured and modelled soil moisture content in the effective root zone of maize in semi-arid Kenya

Difficulties in efficient utilization of seasonal precipitation cause limitations in yields and even total crop failure on rainfed farms in semi-arid East Africa. The objective of the present study was to find out if covering the soil with plant residue mulch at a semi-arid site could retain water in the soil between precipitation events and build dry spell resilience by reducing soil water evaporation and increasing infiltration to deeper soil. Covering soil with plant residue mulch was studied at a smallholder farm in semi-arid Kenya by continuously measuring volumetric soil moisture content with soil sensors at multiple depths in bare soil and in maize (Zea mays L.) plant residue mulched soil. A physically based one-dimensional soil moisture model was calibrated and used to estimate the effect of plant residue mulch on soil moisture over a two-year period (multiple growing seasons). The modelled multiyear time series provides an estimate of the effect residue mulches of different thicknesses have on soil moisture over time. The simple soil moisture model was able to estimate soil moisture in the effective root zone of maize. By comparing measured data from mulched and uncovered soil and by model prediction, it was demonstrated that maize residue mulch conserved soil moisture over time in the effective root zone of maize compared to bare soil. During the two-year period mulching increased the total amount of days when measured relative soil moisture (s) exceeded water stress limit of maize (s*) by 24%–46%. Moisture accumulated in the mulched profile, especially in the deeper layers of the effective root zone. Calculations indicated that further increasing mulch thickness (δm) from 1 to 3 cm would have increased the total days when s >s* 59%. Furthermore, increasing δm from 3 to 5 cm would have resulted in 25% increase in total days when s >s*. According to our calculations mulching (δm > 1 cm) could have maintained s >s* throughout a 19 days dry spell that occurred during the measurement period. The demonstrated moisture conserving effect of mulch increases with δm, but availability of plant residue may set limits on mulch application rates. The results suggest that maize residue mulching is as an accessible and feasible method for conserving soil moisture in the effective root zone in dryland smallholder systems in East Africa.

Effects of optimized subsoiling tillage on field water conservation and summer maize (Zea mays L.) yield in the North China Plain

Farmland water management includes improving soil properties, optimizing root distribution, promoting rainfall and irrigation infiltration, reducing soil water evaporation, increasing water storage, and utilizing precipitation and irrigation efficiently through appropriate tillage methods. These factors are important for summer maize planting systems in areas of extreme water deficiency and hot rainy seasons, such as the North China Plain (NCP). A four-season field experiment was conducted on summer maize to compare the influences and mechanisms of two tillage methods (no-tillage (NT) and subsoiling tillage (ST)) on the water conservation and yield. The ST treatment promoted irrigation and rainfall infiltration, and the water storage capacity in the 2 m soil layer increased by 18.3 mm in the ST treatment over the entire growth period compared to the NT treatment. The field evapotranspiration (ET) and soil evaporation (E) intensities of the ST treatment were 5.6% and 11.5% lower than those of the NT treatment, respectively. Compared to the NT treatment, the ST treatment increased the root width in the 20–40 cm soil layer by 17.8% (on average) and the proportion of root activity by 36.7%. The root dry matter accumulation ratio, root active absorption area, and diameters of the vascular bundle and xylem vessels increased significantly. The average yield of summer maize under the ST treatment was 11.2% higher than that of the NT treatment over the four study years. The water use efficiency was also 16.5% higher in the ST treatment. These results demonstrate that the ST treatment of summer maize improved the infiltration of precipitation and irrigation into the soil, reduced the E, promoted root growth, and increased the maize kernel weight, thereby collectively achieving improved water use efficiency and summer maize yields.

The effect of a prototype hydromulch on soil water evaporation under controlled laboratory conditions

Abstract Organic hydromulches can be an interesting alternative for weed control in perennial crops, but can also reduce soil water evaporation. To examine the effect of a hydromulch layer on soil water content in dry conditions laboratory experiments were conducted at constant 25°C, 40% air RH. Both for small soil containers with a short time course and for larger soil columns (with two sensors at depths of 6 cm and 11 cm) with a longer time course, the presence and also the thickness of hydromulch were significant factors for the temporal evolution of soil water content. Two distinct stages of the evaporation process, the first or initial stage and the last or final stage, were identified, analysed and compared for these experiments. General linear models performed on the soil water content temporal evolutions showed significant differences for the first and last stages at the top and bottom of the soil columns with and without hydromulch. Hydromulch application delayed the evaporation process in comparison with the control. Moreover, the hydromulch layer, which was tested for mechanical resistance to punching, offered enough resistance to prevent its perforation by the sprouts of weed rhizomes.

Characteristics of Soil Moisture and Evaporation under the Activities of Earthworms in Typical Anthrosols in China

Earthworms have an important influence on the terrestrial ecological environment. This study assesses the effect of different earthworm densities on soil water content (SWC) and evaporation in a laboratory experiment. Four earthworm densities (0 no-earthworm, control [C]; 207 earthworms m−2, low density [LDE]; 345 earthworms m−2, medium density [MDE]; and 690 earthworms m−2, high density [HDE]) are tested in soil columns. Results show that cumulative evaporation occurs in the decreasing order of densities: C (98.6 mm) > LDE (115.8 mm) > MDE (118.4 mm) > HDE (124.6 mm). Compared with the control, earthworm activity decreases cumulative soil evaporation by 5.0–20.9%, increases soil temperature to 0.46 °C–0.63 °C at 8:00, and decreases soil temperature to 0.21 °C–0.52 °C at 14:00 on the soil surface. Temperature fluctuations reduce with increasing earthworm densities. A negative correlation is found between cumulative soil evaporation and earthworm density (R2 = 0.969, p < 0.001). Earthworms significantly (p < 0.05) decrease the surface SWC loss (0–20 cm) soil layer but increase the subsoil SWC loss (60–100 cm) by adjusting the soil temperature and reducing soil water evaporation. Earthworm activities (burrows, casts…) improve the soil water holding ability by adjusting soil temperature and reducing soil water evaporation. Thus, the population quantity of earthworms may provide valuable ecosystem services in soil water and heat cycles to save water resources and realize sustainable agricultural development.

Evapotranspiração e produtividade de milho safrinha consorciado com crotalária

Sistemas de consórcio vem como uma alternativa para redução da evaporação da água do solo e consequentemente maior disponibilidade de águas para as plantas. O objetivo deste trabalho foi verificar a influência do consórcio entre a cultura do milho com a crotalária, determinando a evapotranspiração das culturas e avaliando o efeito da competição hídrica nas características produtivas da cultura do milho. O experimento foi realizado no campo experimental da Universidade do Estado de Mato Grosso (UNEMAT), composto por três tratamentos, sendo: T1 - milho solteiro (Zea mays L.), T2 - crotalária solteira (Crotalaria juncea L.), e T3 - milho cultivado em consórcio com crotalária. A evapotranspiração de referência (ETo) foi estimada pela metodologia proposta por Penman-Monteith FAO-56. A evapotranspiração da cultura (ETc) dos tratamentos foram determinadas diariamente através da variação de massa de lisímetros de pesagem, convertida em mm dia-1. A evaporação do solo foi determinada com a utilização de microlisímetros. Foram determinadas as fases fenológicas das culturas para a determinação da ETc nos diferentes estádios de desenvolvimento conforme recomendado pela FAO-56, sendo: Inicial (I), Desenvolvimento (II), Intermediária (III) e Final (IV). Os componentes da produtividade do milho foram avaliados no final do ciclo da cultura. A evaporação do solo foi reduzida em 43,91 mm (26,78%), e a transpiração reduziu em 19,64 mm (14,85%) quando utilizado o sistema de milho consorciado, em relação ao milho em cultivo solteiro. A ETc acumulada foi de 312,00; 436,16 e 422,38 mm, para o milho, crotalária e o consórcio, respectivamente. A produtividade foi de 6739,26 e 4571,85 kg ha-1, para o milho em cultivo solteiro e consorciado, respectivamente.

Glasshouse study of a sprayable, degradable polymer to reduce water use in cotton establishment

This glasshouse pot experiment demonstrated that a new sprayable and degradable polymer reduced soil water evaporation and promoted cotton seedling emergence and establishment. The polymer was tested on two contrasting soils (sandy loam and clay), representative of those used to grow cotton in Australia. Changes in soil water content in non-treated and polymer-treated pots were monitored over 80 days, after surface or subsurface watering. Plant biomass, soil water content and soil chemical properties were determined at harvest. The polymer reduced soil water evaporation by up to 35% in sandy loam and up to 20% in clay, did not compromise seedling emergence and improved plant growth per unit water applied by up to 26.2%. The polymer underwent extensive degradation after 80 days to produce low molecular-weight polymers or oligomers and water-extractable silicon species that may have implications for plant nutrition.

Carbon dioxide and temperature elevation effects on crop evapotranspiration and water use efficiency in soybean as affected by different nitrogen levels

Rising concentration of atmospheric carbon dioxide (CO2) is reported to cause fertilization effect resulting in enhanced crop biomass and yields and may alter the water use of plants. However, factors like air temperature and nitrogen (N) management could modify the feedbacks of CO2 on crop water use. Hence, this field study was carried out in open top field chambers (OTC) for two crop seasons to investigate the interactive effects of climate and N on evapotranspiration, yield and water use efficiency in soybean (Glycine max L.). Soybean crop was grown under three climate conditions (ambient : AC, elevated CO2 : eC, and co-elevation of both CO2 and temperature : eCeT) and four N treatments during July to October 2016 and 2018. Elevation of CO2 was done to the level of 535–540 μmol mol−1, and temperature was elevated by about 2 °C above ambient. The four N levels were N0, N50, N100 and N150 referring to 0, 50, 100 and 150% of recommended N dose (30 kg N ha−1). Crop evapotranspiration (ET) was computed by soil water balance method. The two years’ field study indicated eC and eCeT showed significant yield advantage to the extent of 32-47% over ambient. Significant effect (P < 0.05) of climate was observed on crop ET, profile water storage and water use efficiency (WUE) during both the study years. The effect of N application on these three parameters was significant only in 2016 crop year. Averaged across N treatments, profile soil water storage at harvest was higher by about 5% in 2016 and by 9% in 2018 crop season under eC and eCeT treatments as compared to AC. The crop ET was significantly lower under eC and eCeT in both the years, with significantly higher WUE. The WUE varied from 2.99 to 4.48 kg ha−1 mm−1 in 2016 and from 4.62 to 6.42 kg ha−1 mm−1 in 2018 crop year. Stomatal conductance during major growth period reduced by 21–42% under eC and by 19–31% under eCeT, though it did not reflect in reduced transpiration. The study indicated significantly higher leaf area contributing to reduced soil water evaporation is the major mechanism explaining higher soil water profile under eC and eCeT. Over ambient, the WUE was higher by 48-50% in 2016 and by 37-39% in 2018 under eC and eCeT treatments, which was mostly attributed to higher grain yield.

Effect of viscosity modifiers on soil wicking and physico-mechanical properties of a polyurethane based sprayable biodegradable polymer membrane

Most sprayable polymers are known to undergo wicking into soil due to their low viscosity and have poor efficacy as barriers to reduce soil water evaporation. To minimize wicking, we investigated four different viscosity modifiers (VMs); gelatine (GL), sodium alginate (ALG), xanthan gum (XAN) and polyacrylamide (PAM) in our waterborne polymer formulation (PF). The viscosity modifiers were assessed based on their water solubility, miscibility with the PF and their effect on sprayability.The PF without a viscosity modifier (VM) exhibited a very low viscosity, 7–8 mPa.s, at ambient temperature. Addition of VMs in the range of 2–8 wt% concentration in the PF significantly increased the viscosity. All viscosity modified PF showed varying degrees of a shear thinning characteristic. Viscosity modified PFs showed reduce soil wicking by between 10–90% and, in general, retained mechanical properties similar to the unmodified PF without compromising their sprayability. Among the viscosity modifiers tested, the PF containing 5–9% weight of 2 wt% concentration of XAN provided the best combination of properties for wicking, sprayability, hydrophobicity, membrane formation and tensile strength. It also reduced soil evaporation by more than 60% at a low PF application of 0.58 kg/m2. PF with PAM showed similar results but sprayability was not good. PF with ALG however, required a higher concentration of 8 wt% or increased weight fractions of 2 wt% concentration to show similar effects.

Corn and Sorghum ET, E, Yield, and CWP as Affected by Irrigation Application Method: SDI versus Mid-Elevation Spray Irrigation

Abstract. Greater than 80% of the irrigated area in the Southern High Plains is served by center-pivot irrigation, but the area served by subsurface drip irrigation (SDI) is increasing due to several factors including declining well yields and improved yields and crop water productivity (CWP), particularly for cotton. Not as well established is the degree to which the reduced soil water evaporation (E) in SDI systems affects the soil water balance, water available to the crop, and overall water savings. Grain corn ( L.) and sorghum ( L. Moench) were grown on four large weighing lysimeters at Bushland, Texas, in 2013 (corn), 2014 and 2015 (sorghum), and 2016 (corn). Evapotranspiration (ET) was measured using the lysimeters and using a neutron probe in the surrounding fields. Two of the lysimeters and surrounding fields were irrigated with SDI, and the other two were irrigated with mid-elevation spray application (MESA). The lysimeter-measured evaporative losses were 149 to 151 mm greater from sprinkler-irrigated corn fields than from SDI fields. When growing sorghum, the lysimeter-measured evaporative losses were 44 to 71 mm greater from sprinkler-irrigated fields than from SDI fields. The differences were affected by plant height and became smaller when plant height reached the height of the spray nozzles, indicating that the use of LEPA or LESA nozzles could decrease the evaporative losses from sprinkler-irrigated fields in this region with its high evaporative demand. Annual weather patterns also influenced the differences in evaporative loss, with increased differences in dry years. SDI reduced overall corn water use by 13% to 15%, as determined by neutron probe, while either not significantly affecting yield (2016) or increasing yield by up to 19% (2013) and increasing CWP by 37% (2013) to 13% (2016) as compared with MESA full irrigation. However, sorghum yield decreased by 15% and CWP decreased by 14% in 2014 when using SDI compared with MESA full irrigation due to an overly wet soil profile in the SDI fields and deep percolation that likely caused nutrient losses. In 2015, there were no significant sorghum yield differences between irrigation methods. Sorghum CWP was significantly greater (by 14%) in one SDI field in 2015 compared with MESA fully irrigated sorghum. Overall, sorghum CWP increased by 8% for SDI compared with MESA full irrigation in 2015. These results indicate that SDI will be successful for corn production in the Texas High Plains, but SDI is unlikely to benefit sorghum production. Keywords: Corn, Crop water productivity, Evaporative loss, Evapotranspiration, Irrigation application method, Sorghum, Water use efficiency, Weighing lysimeter.

Effects of pruning and mulching measures on annual soil moisture, yield, and water use efficiency in jujube (Ziziphus jujube Mill.) plantations

Soil desiccation and water shortage are major challenges of rain-fed crop production in the semi-arid areas of the Loess Plateau of China. Mulching and pruning were considered effective strategies to improve harvest by reducing soil water evaporation and plant transpiration rates. In the present study, the possible synergistic effects of the combination of mulching and pruning on soil water status, growth, yield, and water use efficiency were explored in the jujube plant. Field experiments were conducted in a typical hilly semi-arid region over three growing seasons and two dormancy seasons in 2015–2017. The three treatments applied to mountain jujube plantations throughout the year were grassland (CK), regular pruning (PR), and pruning and mulching (PM). Soil water storage (0–200 cm) was higher in the PM than the PR treatment but lower than that of the CK in all three growing seasons. Relative to PR and CK, PM significantly decreased soil water loss during the dormancy season. The soil moisture infiltration depths were 300 cm, 160 cm, and 420 cm in 2016 and 420 cm, 280 cm, and 460 cm in 2017 for PM, PR, and CK, respectively. Soil desiccation was substantially reduced under the PM treatment in the deep soil layer but was less effectively mitigated under the PR treatment. In the CK treatment, soil desiccation appeared at 0–200 cm but was alleviated by heavy rainfall. Fresh fruit yield ranged from 6643–11,056 kg ha−1 for the PM treatment in 2015–2017. This range was 1221–2628 kg ha−1 higher than that for the PR treatment. Water use efficiency was 2.28 kg m−3, 2.05 kg m−3, and 2.22 kg m−3 under the PM treatment in 2015, 2016, and 2017, respectively. These rates were 1.27 × , 1.26 × , and 1.39 × higher, respectively, than those for the PR treatment. These results suggest that the combination of mulching and pruning is an alternative strategy for mitigating soil desiccation in the hilly regions of the Loess Plateau of China. This alternative land management system may be critical for the sustainable cultivation of economically important forest trees in the Loess Plateau region and elsewhere.