Effect of mulching on plant water status, soil salinity and yield of squash under summer-fall deficit irrigation in salt affected soil

Groundwater Salinity Across India: Predicting Occurrences and Controls by Field-Observations and Machine Learning Modeling

Elevated groundwater salinity is unsuitable for drinking and harmful to crop production. Thus, it is crucial to determine groundwater salinity distribution, especially where drinking and agricultural water requirements are largely supported by groundwater. This study used field observation (n = 20,994)-based machine learning models to determine the probabilistic distribution of elevated groundwater salinity (electrical conductivity as a proxy, >2000 μS/cm) at 1 km2 across parts of India for near groundwater-table conditions. The final predictions were made by using the best-performing random forest model. The validation performance also demonstrated the robustness of the model (with 77% accuracy). About 29% of the study area (including 25% of entire cropland areas) was estimated to have elevated salinity, dominantly in northwestern and peninsular India. Also, parts of the northwestern and southeastern coasts, adjoining the Arabian Sea and the Bay of Bengal, were assessed with elevated salinity. The climate was delineated as the dominant factor influencing groundwater salinity occurrence, followed by distance from the coast, geology (lithology), and depth of groundwater. Consequently, ∼330 million people, including ∼109 million coastal populations, were estimated to be potentially exposed to elevated groundwater salinity through groundwater-sourced drinking water, thus substantially limiting clean water access.

Consecutive seasonal effect on yield and water productivity of drip deficit irrigated sorghum in saline soils

Drought stress destructively affects the growth and productivity of sorghum crop, especially under saline soils. Therefore, Field trials were performed to determine the influence of water stress on water productivity (water productivity for grain, (G-WP) and water productivity for forage, (F-WP), yield of sorghum and soil properties in salt-affected soil (8.20 dS m⁻¹) under different sowing dates and irrigation regimes. The summer sowing (SS) was performed on 1 April while fall sowing (FS) was established on 2 August. The irrigation regimes were; 100, 90, 80, and 70% of crop evapotranspiration (ETc). The findings displayed that the fodder and grain yields were increased by 23% and 26% under SS compared to FS over the two seasons 2017 and 2018, respectively. Among irrigation levels, the maximum values of grain and fodder yield were given by 100% of ETc, while a non-significant difference was observed between 100% and 90% of ETc. Moreover, the maximum values of G-WP (1.31%) and F-WP (9.00%) were recorded for 90% of ETc. Interestingly, the soil salinity was decreased in 0–0.6 m depth, and more decline was noted in 0–0.2 m depth using 90% of ETc. The highest salt accumulation withinside the soil profile was recorded under 70% of ETc in comparison to 100% of ETc. Thereupon, under water scarcity, application of 90% of ETc is recommended with SS to save 10% of the applied irrigation water without a significant decrease in grain yield (GY).

Acidified Biochar Confers Improvement in Quality and Yield Attributes of Sufaid Chaunsa Mango in Saline Soil

Mango fruit quality plays a significant role in fruit storage. It also directly affects the economic value of fruit in the national and international markets. However, deterioration of soil health due to low organic matter is a major hurdle for mango growers. Scientists suggest incorporation of organic matter. However, high temperature and low precipitation lead to oxidation of organic residues in soil. On the other hand, biochar is gaining the attention of growers due to its resistance against decomposition. It can improve soil physicochemical attributes. Limited literature is available regarding biochar effects on the quality attributes of mango. Therefore, the current study was planned to investigate the effects of acidified biochar on mango quality and yield attributes in alkaline soil. Five levels of biochar, i.e., 0, 5, 10, 20 and 40 Mg/ha, were applied in a randomized complete block design (RCBD). Results showed that 20 and 40 Mg/ha acidified biochar significantly enhanced fruit retention, sugar contents, ash contents and TSS of mango compared to control. A significant increase in mango fruit weight and yield per plant validated the efficacious role of 40 Mg/ha acidified biochar over control. Furthermore, the maximum significant decrease in fruit juice acidity signified the imperative functioning of 40 Mg/ha acidified biochar in alkaline soil. In conclusion, 40 Mg/ha acidified biochar application can improve mango quality and yield attributes in alkaline soil. More investigations on different soil types, climatic zones and mango varieties are recommended to declare 40 Mg/ha acidified biochar as the best treatment for improvement in the quality and yield of mango fruit in alkaline soils.

Organic Amendment and Mulching Enhanced the Growth and Fruit Quality of Squash Plants (Cucurbita pepo L.) Grown on Silty Loam Soils

Adoption of suitable organic fertilizers and soil mulching are useful tools to enhance soil quality, which will inevitably lead to improved growth and yield of crops. Little is known about the soil organic amendments and Azolla (Azolla pinnata) under soil organic mulching on the growth and yield of squash plant (Cucurbita pepo L.). A comparative study mainly focused on the impacts of organic fertilizer treatments on soil fertility and squash growth under wheat straw mulch was conducted on wooden boxes filled with silty loam soil. Wheat straw, as an organic mulch, and five organic-fertilization treatments were added to the soil. Wheat straw with a size of <2 cm was added to the soil surface with a 2 cm thickness. The fertilization treatments were: control (CO), chemical fertilizer (CF), compost (CT), vermicompost (VC), and dry Azolla (DA). Wheat straw mulch had positive effects on the soil properties, growth, and yield. The maximum fruit yield was obtained from the soil fertilized with DA under wheat straw mulch, while the lowest one was found in the control without mulching. Azolla and organic fertilizers showed a remarkable superiority over the mineral fertilization in increasing the soil fertility as well as the growth and quality of squash fruits; this superiority increased under the wheat straw mulching system. The application of recommended mineral fertilization (CF), compost (CT), vermicompost (VC), and dry Azolla (DA) under wheat straw mulch increased the soil available-N by 2, 20, 12, and 29%, respectively, above the control (CO), while these organic fertilizers without mulching increased the soil available-N by 11, 32, 26, and 48%, respectively. The production of vegetable crops such as squash plants requires the addition of organic fertilizers and mulching to increase yield and quality of fruits.

Foliar Application of Zinc Oxide Nanoparticles Promotes Drought Stress Tolerance in Eggplant (Solanum melongena L.)

Water shortage and salinity are major challenges for sustaining global food security. Using nutrients in the nano-scale formulation including zinc oxide nanoparticles (ZnO NP) is a novel fertilization strategy for crops. In this study, two field-based trials were conducted during 2018 and 2019 to examine the influence of three ZnO NP concentrations (0, 50, and 100 ppm) in eggplant grown under full irrigation (100 of crop evapotranspiration; ETc) and drought stress (60% of ETc). Plant growth, yield, water productivity (WP), physiology, biochemistry, and anatomy responses were evaluated. Drought stress significantly decreased membrane stability index (MSI), relative water content (RWC), and photosynthetic efficiency, thus hampered eggplant growth and yield. In contrast, exogenous ZnO NP to water-stressed eggplant resulted in increased RWC and MSI associated with improved stem and leaf anatomical structures and enhanced photosynthetic efficiency. Under drought stress, supplementation of 50 and 100 ppm ZnO NP improved growth characteristics and increased fruit yield by 12.2% and 22.6%, respectively, compared with fully irrigated plants and nonapplied ZnO NP. The highest water productivity (WP) was obtained when eggplant was irrigated with 60% ETc and foliarly treated with 50 or 100 ppm of ZnO NP, which led to 50.8–66.1% increases in WP when compared with nontreated fully irrigated plants. Collectively, these findings demonstrated that foliar spraying ZnO NP gives the utility for alleviating drought stress effects on eggplant cultivated in saline soil.

Salt Distribution and Potato Response to Irrigation Regimes under Varying Mulching Materials

Water scarcity and frequent drought spells are becoming critical challenges to sustainable agricultural development, especially in arid and semiarid regions. Thus, this work aims to investigate the effect of deficit irrigation and varying mulching materials on soil moisture content, salt distribution, and potato yield. The experiment consisted of three irrigation regimes (I_100%, I_80%, and I_60%) of crop evapotranspiration (ETc), designated as I_100%, I_80%, and I_60% of ETc, and five mulching treatments viz. (i) without mulch (WM), (ii) poultry manure mulch (PMM), (iii) rice straw mulch (RSM), (iv) white plastic mulch (WPM), and (v) black plastic mulch (BPM), which were continued for two consecutive growing seasons. The results showed that soil salinity was affected by mulching and irrigation levels as the salt content increased from the initial soil salinity. Moreover, I_60% recorded the highest salt accumulation in the soil profile for WM treatment compared to the rest of the irrigation and mulching treatments. It was also revealed that PMM remained unmatched by significantly producing the highest potato yield compared to other mulching materials. However, the average potato yield decreased by 13.83% and 29.16% in the 2016 season for I_80% and I_60% and by 12.95% and 30.91% in the 2017 season, respectively, in comparison to full irrigation (I100%). So, when sufficient irrigation water is available, full irrigation (I_100%) and PMM treatment are recommended to achieve the maximum potato tuber yield, which has a minimum impact on increasing salinity. However, when the discharge is insufficient, deficit irrigation (I_80%) and PMM treatment are recommended to conserve 20% of the irrigation water applied with a minimum reduction in tuber yield and a slight increase in soil salinity.

Integrated Use of Potassium and Soil Mulching on Growth and Productivity of Garlic (<i>Allium sativum</i> L.) under Deficit Irrigation

This study was carried out during the winter seasons of 2016 and 2017 at private farm in Beni Suief Governorate, Egypt to investigate the integrative use of potassium levels (24, 48, 72 and 96 kg K2O fed-1) and soil mulching (rice straw and bare soil) on growth and productivity of garlic under three levels of surface irrigation (60, 80 and 100 % of crop evapotranspiration (ETC)). The experimental layout was a spit-spilt plot system based on Randomized Complete Blocks Design. Irrigation levels, potassium rates and mulch types were randomly allocated in the main, sub and sub-sub plots, orderly. The obtained results showed that, the amount of irrigation at 80 and/or 100 % ETC was accompanied increases by plant height, leaves number, leaf area and dry weight plant-1, total bulbs yield, individual bulb weight, cloves weight and number bulb-1 compared to irrigation 60 % ETC. The application of potassium from 24 to 48 and further to 72 and 96 kg K2O fed-1 gave gradual increments in the aforementioned growth and productivity of traits. The rice straw mulch augmented all previous growth, total bulbs yield and its components compared to bare soil. Generally, the 1st order interaction between irrigation percent at 100 and/or 80 % ETC × potassium rate at 96 and/or 72 kg K2O fed-1, irrigation percent at 80 and/or 100 % ETC × rice straw, potassium rate at 96 kg K2O fed-1 × rice straw and the 2nd interaction of irrigation percent at 100 % ETC × potassium rate at 96 kg K2O fed-1 × rice straw mulch had pronounced effects on morphological characters and bulbs yield and its components compared to other combined treatments.

Land suitability modeling for newly reclaimed area using GIS-based multi-criteria decision analysis

Selecting the appropriate land use is one of the most important steps toward achieving sustainable development. The main objective of this research is to develop a new method to overcome the contradiction occurring when using the conventional methods to evaluate land suitability for newly reclaimed areas. A spatial model was developed to assess land suitability for wheat in El-Minia Governorate, Egypt, using integration of modeling and geographic information systems-based multi-criteria decision analysis (GIS-MCDA). Land suitability for wheat was performed using two approaches, namely the proposed model (GIS-MCDA) and the parametric method (square root). According to the square root, 75.0% of the study area was classified as not suitable, while the proposed model revealed that 20.5% of the study area was classified as highly suitable and 61.5% as moderately suitable. In order to examine the validity of the proposed model, a comparison was made between the obtained results of both the proposed model and the square root method with the actual yield of the wheat. The correlation coefficient (r) between actual yield and the estimated yield of the square root method was 0.46, while the proposed model gives higher value (r = 0.95), which proves the validity of the proposed model in estimating land suitability for wheat cultivation. The findings of this research revealed that the integration of modeling and GIS-MCDA adopted by the proposed model provides an effective and flexible technique contributing to improve land suitability assessment for wheat in newly reclaimed areas to be more accurate and reliable.

The effect of gamma irradiation on the properties of cucumber

In this study, the effect of gamma irradiation on the shelf life and properties of cucumber was investigated. These properties include weight reduction, fruit density, juice, tissue firmness, total soluble solids (TSS), total titratable acidity, chlorophyll and vitamin C, pH, marketability, flavor, frostbite and fungal effects. For this purpose, cucumbers were irradiated with dose of 2, 2.5 and 3 kGy. The exposure time was calculated by MCNP4C; the Monte Carlo particle transport code. Three types of fungi (white-Sclerotinia sclerotiorum, gray-Botrytis cinerea and olive-Cladosporium cucumerinum), were used to infect some samples. The chlorophyll and vitamin C preservation abilities were increased to about 3 and 1.4 times, respectively with irradiation treatment. Also, the shelf life was increased about 1 week, while chilling injuries is decreased. Samples' resistance to the fungal growth was evident and the process of fungal growth on the irradiated samples was delayed up to 1 week. The best properties were obtained at the irradiation dose of 2 kGy since it had less effect on flavor, TSS and tissue firmness.

Soil Salt Distribution and Tomato Response to Saline Water Irrigation under Straw Mulching

To investigate better saline water irrigation scheme for tomatoes that scheduling with the compromise among yield (Y_t), quality, irrigation water use efficiency (IWUE) and soil salt residual, an experiment with three irrigation quotas and three salinities of irrigation water was conducted under straw mulching in northern China. The irrigation quota levels were 280 mm (W1), 320 mm (W2) and 360 mm (W3), and the salinity levels were 1.0 dS/m (F), 3.0 dS/m (S1) and 5.0 dS/m (S2). Compared to freshwater, saline water irrigations decreased the maximum leaf area index (LAI_m) of tomatoes, and the LAI_m presented a decline tendency with higher salinity and lower irrigation quota. The best overall quality of tomato was obtained by S2W1, with the comprehensive quality index of 3.61. A higher salinity and lower irrigation quota resulted in a decrease of individual fruit weight and an increase of the blossom-end rot incidence, finally led to a reduction in the tomato Y_t and marketable yield (Y_m). After one growth season of tomato, the mass fraction of soil salt in plough layer under S2W1 treatment was the highest, and which presented a decline trend with an increasing irrigation quota. Moreover, compared to W1, soil salts had a tendency to move to the deeper soil layer when using W2 and W3 irrigation quota. According to the calculation results of projection pursuit model, S1W3 was the optimal treatment that possessed the best comprehensive benefit (tomato overall quality, Y_t, Y_m, IWUE and soil salt residual), and was recommended as the saline water irrigation scheme for tomatoes in northern China.