Mulching Practices Research Articles

Evaluation of Aqua-Crop Model using Onion Crop under Deficit Irrigation and Mulch in Semi-arid Nigeria

The Aqua-Crop simulation model has been playing a crucial role in assessing the performance of the existing strategies for the management of irrigation schemes for improving agricultural water use efficiency. This study evaluated the Aqua-Crop model using Onion crops under deficit irrigation and mulch practices in semi-arid Nigeria. Measurements were taken from the experimental plots which consisted of irrigation and mulch each at 4 levels were used to evaluate the Aqua-Crop model using canopy cover, biomass, yield, actual crop ET, and water productivity of Onion during the 2021 irrigation season. The simulated results from the Aqua-Crop model were evaluated and statistically compared with the experimental results. The model simulated canopy cover with the highest degree of correlation coefficient (0.74 ≤ r ≤ 0.94). The model perfectly predicted Onion yield and biomass under full irrigation irrespective of the mulching. However, the model underestimated Onion yield and biomass at deficit irrigation. The model has perfectly estimated the seasonal actual crop evapotranspiration at different irrigation levels and mulch materials while underestimating water productivity in most of the treatments except at 100% irrigation under white synthetic mulch. However, both model and experimental water productivity were better at white synthetic mulch plots. Therefore, the Aqua-Crop model has proven to be a good Onion crop growth and yield predictor under different irrigation levels and mulch materials which can help improve Onion productivity in water-stressed areas like semi-arid Nigeria.

MODELING THE ONION YIELD RESPONSE TO DEFICIT IRRIGATION AND MULCH USING MULTIPLE REGRESSION MODEL IN SEMI-ARID NIGERIA

Effect of deficit irrigation, mulch practices, crop growth and water use parameters on the yield of Onion was modeled using a multiple linear regression model. The crop evapotranspiration, number of leaves, leaf height and canopy cover of the Onion were used as the independent variables. Onion bulb yield was the dependent variable under four mulching materials (rice straw, RM; wood shaving, WM; white synthetic plastic, SM and no mulch, NM) in the semi-arid region, of Nigeria. The regression analysis revealed that the independent variables in the model predicted the Onion bulb yield significantly (p < 0.05) under mulching conditions, while no mulch plots yielded no significance as indicated by the ANOVA statistic. The overall model degree of determination (r2) of the dependent variable of 0.97, 0.97, 0.98, and 0.81 were obtained under SM, WM, RM, and NM respectively indicating that the multiple regression model predicted the dependent variable satisfactorily. The co-efficient values show that the highest coefficient was obtained at the number of leaves (0.56) followed by crop evapotranspiration (0.33). It was observed that among the four multiple regression models developed, the model obtained with white synthetic plastic mulch produce a better yield. Thus, white synthetic plastic mulch conserved soil moisture thereby improving Onion bulb yield. When the models were tested, a slight overestimation of the Onion bulb yield at both mulched and no mulched regression models was observed as compared with the yield from the field. Therefore, the model obtained with white synthetic plastic mulch produces a better yield.

Effect of fertilizers and mulching on growth and yield of sweet pepper (Capsicum annum L.)

An experiment was carried out to evaluate the effects of fertilizers and mulching on growth and yield of sweet pepper at the Horticulture Farm, Bangladesh Agricultural University, Mymensingh during the period from October, 2018 to March, 2019. Two factors experiment was laid out in Randomized Complete Block Design (RCBD) with 3 replications. The experiment consisted four (4) levels of organic and inorganic fertilizers viz., F1 (Vermicompost), F2 (Recommended dose of NPKS), F3 (50% Vermicompost + 50% Recommended dose of NPKS) and F4 (75% Vermicompost + 25% Recommended dose of NPKS); and three mulch materials viz., M0 (Control), M1 (White polythene) and M2 (Black polythene). Plot size was 1 m x 1 m. The growth and physio-morphological characters, yield attributes and yield were significantly influenced by different types of fertilizers application and mulching practices. F4 treatment (75% Vermicompost + 25% Recommended dose of NPKS) produced maximum yield per hectare (40 t/ha) and F1 (vermicompost) treatment produced minimum yield per hectare (23.07 t/ha). Fruit yield increased 12.49%, 20.01% and 28.44% higher using F4, F3 and F2, respectively compared to control treatment. Mulching material influenced fruit yield where the maximum yield per hectare (40 t/ha) were observed from the M2 (Black polythene). Fruit yield (t/ha) recorded 27.06% and 27.50% higher in M2 and M1, respectively compared to control. In case of combined treatment, the fresh weight of fruit and dry matter were found higher in M2F4 and the lowest in M0F1. The maximum yield per hectare (53.31 t/ha) was found in M2F4 and M2F4 treatment produce 201.75% higher yield (t/ha) compared to control treatment combination M0F1 (17.67 t/ha). The second and third highest was found from M2F3 and M1F4. The highest benefit cost ratio (BCR) was found in M2 F4 and it was 7.49. Black plastic mulch with combined fertilizer (vermicompost and chemical fertilizer) gives higher plant height, yield, dry matter and other yield contributing parameters. Control treatment (no mulch) with only vermicompost gives lowest result in all cases.

Soil-Mulching Influence on Spearmint Oil Yield, Ecophysiological Activities and Essential-Oil Content in Rainfed Environment of Southern Italy

The application of soil mulching is widely used to improve crop productivity within semiarid regions of Mediterranean environments. A field study was conducted during two consecutive cycles of spearmint (Mentha spicata L.) within the rainfed region of Southern Italy to evaluate the effects of straw mulch cultivation practices on crop yields and ecophysiological activities. Four treatments were evaluated: (1) rainfed with straw mulch (RM), (2) rainfed without straw mulch (R), (3) well-watered control plants (W) and (4) well-watered with straw mulch (WM). The rainfed mulch treatment (RM) significantly improved oil yields and ecophysiological activity of the spearmint in comparison with rainfed (R). The rainfed mulch treatment (RM) showed lower inhibition of photosynthesis and smaller diffusive limitations than control treatment, while in rainfed plants (R) photosynthetic activity and diffusive limitations strongly decreased at the end of crop cycle. The average essential-oil content was significantly lower under the W, WM and RM treatments, in comparison to the R treatment, during the full-bloom stages (40 DAT). Instead, at the end of crop cycle, the mulching practice (RM and WM) insignificantly changed the essential-oil content compared with non-mulched well-watered treatment (W), while in rainfed plants (R) the essential-oil content strongly decreased. In addition, rainfed conditions affected the percentage of the three major monoterpenes and decreased the formation of carvone from limonene. Therefore, the current study concluded that straw mulch is an effective management practice to improve growing conditions by decreasing groundwater consumption and to increase oil yields in spearmint within this Mediterranean rainfed region.

Response of maize productivity to nitrogen management and mulching practices

The present experiment was conducted to evaluate the effect of different nitrogen levels and mulch practice on days to physiological maturity, plant height, mean leaf area, mean weeds population, weeds fresh weight, weeds dry weight of maize at Agriculture Research Station Swabi, Khyber Pakhtunkhwa during summer 2019. The experiment was laid out in a randomized complete block design (RCBD) with three replicates. Data was recorded on six quantitative traits i.e. days to physiological maturity, plant height, mean leaf area, mean weeds population, weeds fresh weight, weeds dry weight. Results indicated that Days to physiological maturity, plant height, mean leaf area, mean weeds population, weeds fresh weight, weeds dry weight was significantly altered due to applied treatment. The treatment nitrogen level (N4-150 g.) give high results for the Days to physiological maturity, plant height, mean leaf area, mean weeds population, weeds fresh weight, weeds dry weight as compared to other level of nitrogen, (N1-control), (N2-50g), (N3-100g), (N5-200g). And similarly organic mulch (crop residue) show high result for the Days to physiological maturity, plant height, mean leaf area, mean weeds population, weeds fresh weight, weeds dry weight as compared to inorganic mulch (plastic mulch). It was observed that the nitrogen level (N4-150g) valuable fertilizer and organic mulch show better result as compare to other nitrogen level and inorganic mulch.

Straw strip mulching in a semiarid rainfed agroecosystem achieves carbon sequestration and emission reduction from winter wheat fields

Mulching practices improve soil hydrothermal conditions, which cause changes in soil respiration. Conventional straw mulching has low productivity in areas with relatively low temperatures. Meanwhile, the responses of soil respiration to mulching practices and the relationship between changes in environmental factors caused by mulching and carbon (C) components are not clear in dryland agroecosystem. In this study, we monitored seasonal changes in soil respiration flux and heterotrophic respiration flux of winter wheat fields under different mulching practices in a semiarid rainfed agroecosystem of northern China. The fields were designed for the following three treatments: straw strip mulching (SSM), plastic film mulching (PFM), and non-mulching (CK). Compared to CK, SSM decreased cumulative soil respiration and heterotrophic respiration by 11.6% and 13.3%, whereas PFM increased these values by 12.8% and 8.5%, respectively. SSM significantly decreased soil temperature but increased soil water-filled pore space (WFPS), while PFM significantly increased soil WFPS without affecting soil temperature. Respiration flux was more highly correlated with soil temperature and air temperature than with WFPS and rainfall. SSM and PFM respectively increased by 5.7–9.1% and 10.8–35.5% for grain yield, by 8.1–45.6% and 16.2–69.5% for straw yield, by 8.6–28.6% and 15.1–36.4% for net primary production, and by 23.1–80.6% and 20.3–95.2% for net ecosystem production. Furthermore, mulching practices had a great potential of soil C sequestration and SSM significantly increased soil organic carbon. Changes in ecosystem C components were primarily driven by biomass, followed by soil temperature and air temperature rather than WFPS and rainfall. Based on the sustainability of agroecosystems, SSM increased grain yield of winter wheat while reduced carbon emissions, which showed great potential for C sequestration and may create an environmentally friendly C sink system in a semiarid rainfed agroecosystem of northern China.

Ridge-furrow plastic film mulching enhances grain yield and yield stability of rainfed maize by improving resources capture and use efficiency in a semi-humid drought-prone region

Soil mulching, e.g. straw mulching (SM) and ridge-furrow plastic film mulching (RP), has been reported to promote rainfed crop production in semi-arid regions, but its applicability in improving maize yield and especially yield stability in semi-humid drought-prone regions has been rarely explored. The capture and utilization of thermal, light, water and nutrients resources by maize plants under various soil mulching conditions are also poorly understood. A consecutive five-season field experiment was conducted on rainfed maize in a semi-humid drought-prone region of China during 2015–2019 to assess the effects of SM and RP on soil hydrothermal conditions, radiation interception, photosynthesis, evapotranspiration and grain yield stability, profitability and resources use efficiency compared with non-mulching (NM). The results showed that RP enhanced soil hydrothermal conditions, promoted the conversion of water from soil evaporation to plant transpiration and improved water productivity by 10.9%−203.2% compared with NM (P < 0.05). Although the growth duration was shortened, the accumulative soil thermal time and intercepted photosynthetically active radiation under RP were still 4.4% and 3.9% higher, with average increases in thermal time use efficiency by 23% and radiation use efficiency by 24%, which resulted in significantly higher nutrients accumulation (by 6.7%−19.7% for nitrogen and 4.1%−42.0% for phosphorous), grain yield (by 9.5%−186.4%) and yield stability (by 38.1%). These improvements were particularly pronounced in normal and dry years (2015, 2016 and 2017). No significant difference existed in maize’s capacity of absorbing water and nutrients and maize productivity between SM and RP under sufficient precipitation supply (2018 and 2019). The average net profit was highest under RP, especially in dry and normal years, while SM could achieve comparable net profit to RP in wet years. Overall, RP was preferable for rainfed maize production in semi-humid drought-prone regions in any precipitation year, while SM can be an alternative mulching practice in wet years. These results can improve our understanding of how RP and SM enhance rainfed maize productivity by improving resources capture and use efficiency.

Analysis of UV–Vis spectral characteristics and content estimation of soil DOM under mulching practices

Dissolved organic matter (DOM), which is generally expressed in terms of dissolved organic carbon (DOC), is a key indicator used to monitor the short-term dynamics of soil quality. However, its content and molecular composition are strongly influenced by agricultural practices, and the determination of DOC content is cumbersome and expensive. A field experiment with three treatments, including (i) no mulching (CK), (ii) gravel mulching (GM) and (iii) film mulching (FM), was selected to study the content and composition characteristics of DOC under different agricultural practices using ultraviolet visible (UV–Vis) technology. The results showed that the GM and FM treatments significantly decreased the DOC contents in topsoil (0–20 cm) by 6.15% and 12.18%, respectively, in comparison with the control. The FM treatment significantly decreased the values of specific UV absorbance at 254 nm (SUVA254), 260 nm (SUVA260) and Chromophoric DOM (CDOM) in each soil layer, indicating the aromaticity, hydrophobicity and CDOM content in the FM treatment were significantly decreased in each soil layer. To establish an accurate model for rapid determination of soil DOC, Spearman correlation analysis was performed on normally and non-normally distributed datasets, and linear regression analysis was utilized for modeling with normalized data. The results of linear regression analysis showed that the regression models established among CDOM/DOC, CDOM, SUVA254, SUVA260, and specific UV absorbance at 280 nm (SUVA280) had a high degree of fit, with coefficients of determination (R2) all exceeding 0.95. The model validation results showed that the regression model established between CDOM/DOC and CDOM had the highest accuracy with the lowest root mean squared error (RMSE) (3.58 mg kg−1) and the lowest relative error (RE) (2.74%), which was DOC = 58.065 + 184.355 × A(355) mg kg−1. The results showed that the estimation of soil DOC can be achieved with good prediction using UV–Vis technology. This study highlights the potential of UV–Vis spectroscopic technology to rapidly estimate soil DOM in agriculture.

Effect of film mulching on crop yield and water use efficiency in drip irrigation systems: A meta-analysis

Improving water use efficiency is an effective way to conserve water in agriculture. Drip irrigation is a water-saving irrigation technology that has been adopted worldwide. Film mulching can prevent undesired water vaporization losses and enhance soil surface temperature. This study used a meta-analysis to assess the effects of mulching on crop yield (CY) and water use efficiency (WUE) under drip irrigation to determine whether a superposition effect occurs when combining film mulching and drip irrigation and whether the limiting factors of film mulching play a positive role in agricultural production. The results showed that film-mulching drip irrigation (FMDI) increased CY and WUE by about 20% and 30%, respectively, compared with nonmulching drip irrigation (NMDI). These improvements were affected by climatic conditions (climate), soil conditions (SC), crop type (CT), water consumption (WC), and mulching material (MM). For climate, film mulching was most effective in areas with temperature (Te) values below 10 °C and rainfall (RF) less than 400 mm, increasing CY by 17.6% and WUE by 16.2%. For SC, FMDI improved CY and WUE the most in medium-textured (loam) soil types with less than 17% plant available water capacity. As water consumption increased, the effect size of CY and WUE under FMDI decreased. For CT, FMDI increased vegetable CY (13.3–17.5%) and field crop WUE (12.3–53.7%). MM had no significant effect on improving CY or WUE. This study provides a reference for the practice of film mulching under drip irrigation conditions.

Effects of bio-mulching on wheat soil microbial community and carbon utilization efficiency in southwest China

Bio-mulching is a common agricultural practice in southwest China to improve crop productivity and soil fertility. In this study, a field experiment to investigate the effects of Chinese milk vetch (Astragalus sinicus L.) mulching and soybean straw retention (at the rate of 2250 and 4500 kg ha−1) on wheat soil microbial community and carbon utilization efficiency was conducted in southwest China. Results showed that the alpha diversity indices (Chao and Shannon) of bacteria and fungi in milk vetch mulching treatment were significantly increased in the wheat non-rhizosphere soils compared with control soil (without mulching). Within the bacterial community, the relative abundance of Actinobacteria and Chloroflexi was significantly increased by milk vetch mulching over the control, while the relative abundance of Acidobacteria, Firmicutes, Verrucomicrobia, and Gemmatimonadetes were significantly decreased in both wheat rhizosphere and non-rhizosphere soil. Within the fungal community, the relative abundance of Basidiomycota was significantly increased in milk vetch mulching treatment than that of control. By contrast, the differences in microbial diversity and community structure between the soybean straw retention and control were not distinctive. The correlation analysis revealed that wheat soil moisture, soil nitrate content, microbial biomass carbon, dissolved organic carbon and nitrogen content were closely related to the soil microbial community structure under different mulching practices. Results of the Biology ECO-plate revealed that all bio-mulching practices have enhanced the carbon source utilization rate. In addition, the relative abundance of Actinobacteria and Basidiomycota has a positive correlation with the metabolism rate of carbon substrates, such as glycyl-L-glutamic acid, I-erythritol, D-xylose, and α-cyclodextrin. Overall, our results suggested that bio-mulching, especially milk vetch mulching, has changed greatly the soil microbial community structure and function in the wheat rhizosphere.

Response of Fungal Sub-Communities in a Maize-Wheat Rotation Field Subjected to Long-Term Conservation Tillage Management.

Conservation tillage is an advanced agricultural technology that seeks to minimize soil disturbance by reducing, or even eliminating tillage. Straw or stubble mulching in conservation tillage systems help to increase crop yield, maintain biodiversity and increase levels of exogenous nutrients, all of which may influence the structure of fungal communities in the soil. Currently, however, the assembly processes and co-occurrence patterns of fungal sub-communities remain unknown. In this paper, we investigated the effects of no-tillage and straw mulching on the composition, assembly process, and co-occurrence patterns of soil fungal sub-communities in a long-term experimental plot (15 years). The results revealed that combine straw mulching with no-tillage significantly increased the richness of fungi but not their diversity. Differential abundance analysis and principal component analysis (PCA) indicated that tillage management had a greater effect on the fungal communities of abundant and intermediate taxa than on the rare taxa. Available phosphorus (AP) and total nitrogen (TN) were the major determinants of fungal sub-communities in NT treatment. The abundant fungal sub-communities were assembled by deterministic processes under medium strength selection, while strong conservation tillage strength shifts the abundant sub-community assembly process from deterministic to stochastic. Overall, the investigation of the ecological network indicated that no-tillage and straw mulching practices decreased the complexity of the abundant and intermediate fungal networks, while not significantly influencing rare fungal networks. These findings refine our knowledge of the response of fungal sub-communities to conservation tillage management techniques and provide new insights into understanding fungal sub-community assembly.

Photosynthetic and growth characteristics of apple and soybean in an intercropping system under different mulch and irrigation regimes in the Loess Plateau of China

The shortage of and intense competition for water and light are the main factors restricting the productivity of agroforestry systems in the Loess Plateau of western Shanxi, China. The combination of soil mulch and irrigation in agroforestry systems can regulate the interspecific relationships and increase the productivity of the component crops. However, the effects of mulch and irrigation regimes on the photosynthetic physiological characteristics of the agroforestry system and its synergistic mechanisms are still unclear. A 3-year experiment with two factors, mulch and irrigation, was conducted to investigate the effects of different mulch practices and irrigation levels on the photosynthetic characteristics, growth indices, and interspecific relationships of a fruit tree-crop intercropping system. An apple–soybean intercropping system was selected as the research object, and two mulch types [straw mulch (M1) and plastic mulch (M2)] and four maximum irrigation levels [no irrigation (W0), 55% (W1), 70% (W2), and 85% (W3) field capacity (Fc)] were tested. No mulch together with no irrigation was the control treatment (CK). The results showed that there was no photosynthetic siesta phenomenon in the intercropping system, and the daily variations of the net photosynthetic rate (Pn) and transpiration rate (Tr) were unimodal. The mean values for Pn, Tr, and leaf photosynthetic efficiency (PUE) of the apple and soybean under the M2 treatment were generally higher than under the M1 treatment, whereas Tr and PUE increased as the amount of irrigation increased. In 2017–2018, the maximum mean Pn values for both apple and soybean were observed under the M2W2 treatment, whereas in 2019, they were observed under the M2W3 treatment. The Pn, Tr, and leaf intrinsic water use efficiency (WUEi) of soybean correlated positively with the distance from the trees, whereas PUE correlated negatively with it. Mulch and water replenishment increased apple shoot growth and the height, leaf area index, and yield of soybean, especially under plastic mulch. A principal components analysis found that the M2W2 treatment had the highest comprehensive benefits in 2017–2018, whereas in 2019, the highest were achieved with the M2W3 treatment. Therefore, to optimize the photosynthetic efficiency and yield of the apple–soybean intercropping system in the loess region of western Shanxi, we suggest a combination of plastic mulch and maximum irrigation of 70% Fc in normal years, but maximum irrigation should be increased to 85% Fc in dry years.

Hydrothermal conditions impact yield, yield gap and water use efficiency of dryland wheat under different mulching practice in the Loess Plateau

Mulching practice reduces evaporation, modifies soil temperature and thereby affects crop yields. But the effects of mulching practices on moisture preservation and yield increase are not consistent under different precipitation and temperature conditions. The Loess Plateau spans a wide range, with distinct spatiotemporal variation in its hydrothermal conditions, so the reported effects of mulching are sometimes contradictory. A meta-analysis was carried out to evaluate the impact of plastic film mulching (PFM) and straw mulching (SM) on grain yields and water use efficiency (WUE) of wheat based on data from 74 peer-reviewed publications. The results showed that PFM and SM were significantly increased wheat yield and WUE compared with no-mulching (CK). The impact of mulching on wheat yields was also affected by temperature and precipitation. PFM led to a large yield and WUE increase under low-temperature conditions, the yield and WUE under SM was significantly affected by temperature and precipitation. Compared with PFM, SM showed no yield or WUE increasement effect under high temperature with low precipitation (> 10 °C, ≤ 350 mm) or low temperature with high precipitation (≤ 10 °C, > 350 mm). Meanwhile, our study found that PFM may reduce the yield gap between potential and actual yields compared to SM. These results have important implications for choosing proper mulching practices to increase wheat yields and WUE in agricultural production under local hydrothermal conditions.

Practice cost and size differences in invasive plant management strategies: An empirical analysis of US Great Plains states

Grassland conservation of the Conservation Stewardship Program in the United States (US) is one of the largest cost-sharing initiatives for protecting grazing land from invasive and woody plants. The practice cost and unit size of various invasive and woody plant management strategies, such as mulching, brush management, and prescribed burning, are different from state to state. We aimed to compare and examine the association between practice cost ($/acre[ac]) and standard unit size of practice (acre) of mulching, brush management, and prescribed burning strategies in nine US Great Plains states, including Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming. We estimated state-level average practice cost and unit size of mulching, brush management, and prescribed burning strategies using the conservation payment data of the Natural Resources Conservation Service (NRCS) to determine a cost-minimizing management strategy. A linear regression model was used to understand the association between practice cost and unit size of different management strategies and states. Practice cost and unit size differ by invasive and woody plant management strategy and Great Plains state. In the nine US Great Plains states, prescribed burning costs less on average ($29/ac) than mulching ($222/ac) and brush management ($152/ac) but covers a larger area on average (239 acres/unit) than mulching (3.19 acres/unit) and brush management (132 acres/unit). From the regression results, we also find a significantly negative association between practice cost and unit size (Coef. = -0.18, p<0.05). For prescribed burning, the practice cost is significantly lower (Coef. = -148.70, p<0.00) than the reference category of mulching. Our findings imply a policy idea that prescribed burning could be a cost-minimizing and high-coverage strategy than brush management in managing woody invasion under existing cost-unit size framework. Alternatively, expanding the typical unit sizes of a small covering strategy such as mulching could be another policy option for further assessment.

Nitrogen Dynamics and Sweet Potato Production under Indigenous Soil Moisture Conservation Practices in the Leeward Kohala Field System, Hawai’i Island

Intensive cultivation of ‘uala (sweet potato) in the Leeward Kohala field system on Hawai’i Island supported substantial populations of Native Hawaiians prior to its abandonment in the 19th century. Productivity is influenced by the heterogeneity of the climate and biogeochemical soil characteristics across the substantial ecological gradient. Agricultural infrastructure and associated practices were developed to manage crop production eventuating from the variation in inter- and intra-annual rainfall. Mechanisms of sustaining soil nitrogen (N) are still unclear; however, a pronounced source of N is soil organic matter decomposition. This study investigated in situ the effects of indigenous Hawaiian mulching practices against two control treatments on soil moisture and temperature dynamics to facilitate N mineralization in soil mounds cultivated with ‘uala. Field experiments were set in two agricultural restoration plots with distinct climatic and soil characteristics. Data included soil moisture and temperature, soil and plant N, growth and development of ‘uala, and real-time weather data. Concurrently, N mineralization was also investigated under controlled conditions. All indigenous mulching treatments were found to significantly increase soil moisture, regulate temperature variation, and improve N availability compared to control. Differences in soil properties between treatments translated to significant differences in above-ground biomass. The data suggest that these differences would extend to tuber production, but the use of a long-gestation variety limited tuber production in the study. Increased temperatures in the controlled experiments were observed to increase inorganic N significantly, but less substantially than soil moisture. Indigenous practices in the region could have greatly mitigated plant stress due to moisture, temperature, and N availability, increasing productivity and reducing the variability of the Leeward Kohala Field System.

Effects of soil preparation and mulching practices together with different urea applications on the water and nitrogen use of winter wheat in semi-humid and drought-prone areas

Soil preparation and mulching practices in combination with slow-release urea application are important measures for agricultural yield enhancement. However, slow-release urea may cause a yield reduction due to insufficient fertility in early crop growth. We considered whether the ridge-furrow plastic-mulching (RFP) system using different mulch colors could offset this disadvantage. An experiment was conducted using a randomized split-plot design with three soil preparation and mulching practices as the main-plot treatments in combination with three different urea applications as sub-plot treatments. The three soil preparation and mulching practices were flat cropping without mulch (F), the RFP system with white plastic mulch over the ridge (W), and the RFP system with black plastic mulch over the ridge (B); the three urea applications were no urea (N0), slow-release urea (NS), and ordinary urea (NU). The results showed that compared to F, the RFP system (especially B) could increase the use of precipitation and reduce soil water depletion, which ultimately increased the water productivity (WP) of winter wheat. In addition, the nitrogen use efficiency of NS was further improved under the RFP system, while there was essentially no difference between the two different urea types under F. In summary, B could take full advantage of NS to coordinate the relationship between effective spikes per unit area, grains per spike, and 1000-grain weight, maximizing the WP, nitrogen use efficiency, and grain yield. Between 2016 and 2019, the WP and grain yield of B-NS increased by 79.2–107.0% and 75.7–87.0%, respectively, compared to the lowest value (F-N0). The nitrogen agronomic efficiency (NAE), nitrogen physiological efficiency (NPE), nitrogen recovery efficiency (NRE), and nitrogen partial factor productivity (NPFP) of B-NS increased by 116.1–123.3%, 28.5–34.8%, 66.1–71.9%, and 44.1–53.2%, respectively, compared with the lowest value (F-NU).

Bioenergy sorghum as balancing feedback loop for intensification of cropping system in salt-affected soils of the semi–arid region: Energetics, biomass quality and soil properties

Soil salinity and limited freshwater availability are the challenges for intensification of the cropping system in semi–arid regions with monsoonal climate. Augmenting freshwater with saline groundwater could be an alternative strategy for increasing cropping intensity. This experiment was conducted to test the impact of deficit saline water irrigation (DSI) with mulching and tillage on root zone salinity and performance of rainfed bioenergy sorghum [Sorghum bicolor (L.)] followed by saline water irrigated wheat. Three tillage treatments viz. zero–reduced (RT), conventional–conventional (CT), and zero–zero (ZT) were practiced in the main plot and irrigated wheat [comprising of saline water (ECiw 8.0 dS m–1)] with 60%, 80% and 100% of water requirement (WR) – rainfed sorghum and mulch (no mulch and 5.0 Mg rice straw ha–1) in subplots. Deficit saline irrigation, RT, and mulching reduced the salinity by 1.5 times in the second rotation. Ca2+ and Mg2+ and K+ content in soil solution were increased under RT and ZT, respectively compared to CT. The rice straw mulching increased the CO32–, HCO3– and K+ concentration (P < 0.005). Irrigation with 100WR saline water increased Ca2+ and Na+ content in soil solution compared to DSI. The DSI at 60WR with mulch in reduced tillage produced greater biomass. The saline irrigation increased the lower heating value of the sorghum biomass compared to pond water irrigation. The energy output of the RT and ZT was 16.8% higher than CT. Mulching also caused a 7.9% increase in energy output. RT with 60WR and mulch produced higher energy. Energy input associated with production systems involving different tillage and mulching practices was determined at 12.0 – 28.3 GJ ha–1. The bulk of the energy input was through crop residue (50.2–54.2%) followed by mineral fertilizers (28.0–30.2%) and seeds (8.4–9.1%). Mulching reduced the energy efficiency ratio. RT produced a similar amount of holo-cellulose while the greater value of lignin compared to CT. Different soil variables explained ~35% variability in biomass quality. This study concludes that integration of reduced tillage, deficit irrigation, and mulching is effective in the intensification of the cropping system and bioenergy sorghum can be a candidate crop in rotation with saline water irrigated wheat in a semi-arid region. These results also showed the potential of crop diversification in the rainfed region for increased feedstock biomass production and efficient use of saline water.

Estimating Evapotranspiration of Maize under Different Management Practices in a Semiarid Tropical Area Using the Soil Water Balance Method

Smallholder farmers in semiarid areas face low and erratic rainfall and need field management practices that conserve water in the root zone. This work evaluated the effect of mulching and DD (deep tillage) practices as a way to conserve soil moisture and thus improve water availability and maize crop yield in this water-scarce environment. The field experiment was carried out in which the soil moisture content (SMC) was monitored and the other water balance components were measured to quantify the crop ET with the soil water balance (SWB) method. The components of the SWB (rainfall, supplemental irrigation, runoff, deep percolation and change of soil moisture content) were measured for three consecutive seasons of 2018-2019, i.e. two long rain seasons (Masika 2018 and 2019) and one short-rains season (Vuli 2018). The estimation of the deep percolation (DP) involved calculating water fluxes from hydraulic properties measured in the laboratory and from hydraulic gradients measured with tensiometers in the field plots. Treatments significantly affected ET (p ’ cultivation, FC), mulching (FCM) reduced evapotranspiration by 14% and 18% during more water-stressed seasons of Vuli 2018 and Masika 2019. The ET reduction among the treatments was in line with the reduction in soil evaporation, as reflected in the results (of the other article of the same work). The crop transpiration was observed higher, which was consistent with the higher canopy cover observations for the two treatments relative to the FC treatment. Also, while the mulch practice did not affect ET during the first and less water-stressed season of Masika 2018, DD reduced it by 9% and showed no effect during other seasons.

The lagging movement of soil nitrate in comparison to that of soil water in the 500-cm soil profile

The combination of forage-crop rotation with conservation tillage has long been known to result in proven productivity and sustainability, but less information is available on the influence of long-term conservation tillage practices on the movement of soil water and residual nitrate at deep soil depths in forage-crop rotation systems. In this study, we measured the changes in soil water storage, residual soil nitrate accumulation and their relationship to study the long-term effects of tillage and mulching practices on regional nitrogen management in maize (Zea mays L.)-wheat (Triticum aestivum L.)-common vetch (Vicia sativa L., annual legume forage) rotation system. Soils were collected from the 500-cm soil profile at the harvest stage of the maize and common vetch after 19 years of continuous conventional tillage (T), conventional tillage followed by straw mulching (TS), no tillage (NT), and no tillage followed by straw mulching (NTS) on the Loess Plateau, China. The results showed that the NT practices increased soil water storage by 3.07% compared with the T practices in the maize field, mulching practices increased soil water storage by 3.47% compared with no mulching practices in the common vetch field, and the improvement effect was mainly concentrated in the deep soil layer (150–500 cm). When compared with no mulching, straw mulching practices increased residual soil nitrate accumulation by 51.20 kg ha−1 at shallow soil depths (0–120 cm) but decreased this accumulation by 206.09 kg ha−1 at deep soil depths (120–500 cm) in the maize field; however, straw mulching decreased nitrate accumulation by 16.25 kg ha−1 throughout the whole profile (0–500 cm) in the common vetch field. The NT practices decreased residual soil nitrate accumulation by 131.65 kg ha−1 compared with the T practices in the maize field but had no effects on the common vetch field in the 0–500-cm soil profile. Greater changes in soil residual nitrate accumulation appeared at depths of 200–500 cm than at other depths. Moreover, according to structural equation model, nitrite accumulation was limited by soil water storage. Soil nitrate peaked at deeper soil depths in the NT (90–120 cm) and TS (250–300 cm) treatments than in the T treatment (60–90 cm), whereas the NTS treatment resulted in no nitrate accumulation peak across the whole soil profile. Soil water recharge and depletion were deeper in the NT and TS treatments than in the T treatment, and this effect could limit the further leaching of soil nitrate into deep soil. The depth of soil water recharge was deeper than the depth of nitrate accumulation, and the vertical movement speed of soil residual nitrate was slower than that of soil water. Therefore, the downward movement of soil nitrate lagged behind that of soil water. Together, these results demonstrated that the NTS treatment exerted the strongest effect on maintaining soil water and decreasing residual nitrate accumulation at deep soil depths, which will be favorable for improving regional N management and assessing N budgets in agroecological systems on the Loess Plateau.

Does plastic mulching reduce water footprint in field crops in China? A meta-analysis

Excessive use of water resources is threatening agriculture, other business and populations in China, India and USA, and crop production is expected to play a critical role in the sustainable use of water. In China, plastic mulching is widely employed in crop production, but its impact on agricultural water footprint has not been properly described. A meta-analysis was performed to examine how plastic mulching influences volumetric water availability (VWA), global stress-weighted water footprint per unit of output energy (WFo), and per unit of net economic return in crop production (WFe). Data extracted from 394 published studies in maize (Zea mays L.), wheat (Triticum aestivum L.), and potato (Solanum tuberosum L.) were used in the meta-analysis on crop production at the regional scale and across a range of N fertilization gradients in China. Plastic mulching reduced VWA by 15.3%, 14.1%, and 16.3% in maize, wheat, and potato, respectively, when compared to non-mulching practice, with corresponding reductions of WFo by 33.3%, 28.1%, and 32.1% and of WFe by 14.8%, 31.1%, and 31.0% in maize, wheat, and potato, respectively. Water footprint for crop production increased first and then decreased over the past four decades in China, and was greater in northwest and north central regions of China than in other regions. Under moderate and high N fertilization (>100 kg N ha−1) in dry regions, plastic mulching increased the impact on VWA, thereby reducing WFo and WFe. Water footprint for the production in potato and maize was lower than that in wheat. The meta-analysis demonstrated that plastic mulching practices reduced water footprint while lowering VWA. Therefore, plastic mulching has potential for saving water resource when appropriate growing region and N fertilizer applications are considered.