Soil Moisture Depletion Research Articles

A new exploration for accurately quantifying the effect of afforestation on soil moisture: A case study of artificial Robinia pseudoacacia in the Loess Plateau (China)

Soil moisture is crucial for the sustainable development of artificial forests in arid and semi-arid regions, and an accurate quantification of the influence of artificial vegetation on soil moisture has profound implications in the assessment of the ecological effects of artificial vegetation in arid and semi-arid regions. This study analyzed the variations in the soil moisture content (SMC) following the conversion of croplands into forests with Robinia pseudoacacia (RP) at different vegetation ages (5, 20, and 40 years) in the Loess Plateau and attempted to regard abandoned cropland (AL) with different restoration years (5, 20, and 40 years) as control samples to accurately quantify soil moisture depletion in the absence of RP at different ages. The results showed that the SMC of the 0–500-cm soil profile, which the zone that supports the whole growth processes for RP in the study area, was in a state of depletion, with an average water depletion of 40.75% and a maximum water depletion of 68.39%. RP mainly consumes shallow soil moisture (0–100 cm) during the early stage of afforestation, and with increases in forest age, RP mainly consumes soil moisture at increasingly deeper layers (100–500 cm). The largest soil water consumption in the presence of RP was observed at 150–180 cm. As RP forests grow, the water demand increases and shifts from the upper to deeper soil layers, and when the deeper soil water consumption reaches a certain level, the water consumption shifts upward. This phenomenon results in different degrees of drying between surface and deep soil layers over time. Abandoned cropland has a decreased influence on the SMC of the whole profile and appears to benefit water conservation at deeper soil layers in the mid-recovery period. Therefore, the vegetation succession in control plots should be considered to enhance the accuracy of the findings in future soil moisture research and afforestation practice. To maintain the sustainability of afforestation, succession should progress from less to more advanced plants (grasses-shrubs-forests), and the cultivation of shallow-rooted herbaceous plants (the main herb species in abandoned croplands) and natural restoration should be prioritized. Moreover, the ecological importance of natural restoration should be considered, the degree of blind artificial transformation should be reduced, and the strong adaptability and evolutionary ability of tree species to survive should receive proper attention.

Performance Assessment of Five Different Soil Moisture Sensors under Irrigated Field Conditions in Oklahoma

Meeting the ever-increasing global food, feed, and fiber demands while conserving the quantity and quality of limited agricultural water resources and maintaining the sustainability of irrigated agriculture requires optimizing irrigation management using advanced technologies such as soil moisture sensors. In this study, the performance of five different soil moisture sensors was evaluated for their accuracy in two irrigated cropping systems, one each in central and southwest Oklahoma, with variable levels of soil salinity and clay content. With factory calibrations, three of the sensors had sufficient accuracies at the site with lower levels of salinity and clay, while none of them performed satisfactorily at the site with higher levels of salinity and clay. The study also investigated the performance of different approaches (laboratory, sensor-based, and the Rosetta model) to determine soil moisture thresholds required for irrigation scheduling, i.e., field capacity (FC) and wilting point (WP). The estimated FC and WP by the Rosetta model were closest to the laboratory-measured data using undisturbed soil cores, regardless of the type and number of input parameters used in the Rosetta model. The sensor-based method of ranking the readings resulted in overestimation of FC and WP. Finally, soil moisture depletion, a critical parameter in effective irrigation scheduling, was calculated by combining sensor readings and FC estimates. Ranking-based FC resulted in overestimation of soil moisture depletion, even for accurate sensors at the site with lower levels of salinity and clay.

Shade netting reduces sunburn damage and soil moisture depletion in ‘Granny Smith’ apples

The benefits associated with the use of protective netting for apple orchards have been assessed in several growing regions, but no studies exist for Washington State, USA. This region experiences semi-arid conditions characterized by long days, high light intensity and high temperatures which increases the risk of plant stress and fruit sunburn damage. The aim of this study was to assess the effect of anti-hail nets on orchard microclimate, soil moisture and fruit sunburn. Seven-year-old ‘Granny Smith’/‘M9-T337’ apple trees were covered in 2014 with 20% white shade net sheltering a rectangular area. Uncovered trees served as control. Shade net reduced the maximum daily photosynthetically active radiation (PAR) by 32%, with a maximum PAR value on a sunny day of 1649 and 1222 μmol m-2 s-1 in the control and netted areas, respectively. Canopy air temperature was slightly lower during the day and higher at night under the net compared to the control. Shade nets reduced soil moisture depletion at 0-30 cm depth, resulting 20% higher than the control. No significant differences were observed deeper in the soil profile. Netting significantly decreased fruit sunburn, with 92% of harvested fruit having no sunburn damage compared to control in which 51% had no sunburn damage in 2014. Although preliminary, these results show that shade netting has the potential to reduce sunburn damage in ‘Granny Simith’ apples and water requirements in semi-arid environments and might represent an important tool for increasing yields of high quality fruit.

Growth and nutrient content of Echinacea purpurea as affected by the combination of phosphorus with arbuscular mycorrhizal fungus and Pseudomonas florescent bacterium under different irrigation regimes

The excessive use of chemical fertilizers has caused many environmental problems and threatens the health of the human communities at the global level. However, the use of some beneficial soil microorganisms in addition to supplying nutrients to plants helps protect the environment. In order to achieve this goal, the effects of different irrigation regimes and application of phosphorus (P) fertilizer, with mycorrhizal arbuscular fungus (AMF) or Pseudomonas fluorescens bacterium (PFB), were studied on the growth and nutrients of Echinacea purpurea. The main factor included soil irrigation after 25, 50 and 75% of soil moisture depletion and a sub-factor of P supplied in six levels (100% chemical P, 50% P + AMF, AMF, 50% P + PFB, PFB and a control test without P fertilizer). Results showed that an increase in drought intensity reduced the absorption of nutrients and relative water content (RWC), while ion leakage increased in the leaf of E. purpurea. The AMF had a more clear effect on the N, Cu, Mn, and Fe, but PFB was more effective in an increase of Zn. With the use of PFB in the second harvest, the amount of leaf and root Zn was increased by 30.39% and 31.88%, respectively. Although 100% chemical P could increase more P concentration in the root, the combination of P fertilizer with AMF transferred more P from root to leaf. In the first and second harvest, a combination of P with PFB respectively increased the plant biological yield by 10.77% and 17.33% as compared to control. Vegetative traits, Mn, and Zn illustrated a significant increase in the second harvest. Finally, the results showed successful coexistence of bio-fertilizers with E. purpurea in increasing the content of nutrients, improving water absorption, and reducing the adverse effects of drought stress.

Validation of irrigation scheduling for cultivation of irrigated wheat in semi-arid climatic condition of Ethiopia

ABSTRACTThis study was conducted for three years (2014-2016) to validate irrigation scheduling of irrigated wheat cultivation to determine appropriate irrigation regime. The experiments were irrigation scheduling based on CROPWAT Model 8.0 and validation on field trial. The treatments were arranged in randomized complete block design with three replications. The field trial was involving three irrigation regime treatments were used for comparison. The treatments were Treatment 1 (T1): Optimal irrigation regime as determined by Cowpat for windows that provides irrigation water of D1=50mm at an interval of I1=7 days, Treatment 2(T2): Optimal irrigation regime as determined by Cowpat for windows that provides irrigation water of D2=67mm at an interval of I2=10 days. Treatment 3(T3): Optimal irrigation regime as determined by Cowpat for windows that provides irrigation water of D3=108.3mm at an interval of I3=15 days. Treatment 4(T4): An irrigation regime that provides irrigation water at critical soil moisture depletion and an amount that would refill the soil moisture depletion to field capacity. Result indicated that grain yield was significantly affected by irrigation levels. Irrigation regime of Treatment 4 produced higher grain yield 2400 kg/ha and 20.0q/ha in 2015 and 2016 cropping season. The highest mean yield of wheat (2200 kg/ha) was obtained from critical moisture refill field capacity irrigation application. Whereas, the lowest mean yield (1778 kg/ha) was obtained from T3, 7 days irrigation interval and 50mm irrigation application. This indicates that yield of wheat decrease with decreasing water amount and short interval frequency. Irrigation scheduling based on cowpat model with irrigation regime that provides irrigation water at critical soil moisture depletion and an amount that would refill the soil moisture depletion to field capacity found promising optimum wheat scheduling under Werer and similar areas.

Okra Crop Response Under Subsurface Drip and Conventional Furrow Irrigation with Varying N Fertilization

ABSTRACTThere is a growing concern about excessive use of nitrogen (N) and water in agricultural system with unscientific management in Indian and developing countries of the world. Field experiments were conducted on the lateritic sandy loam soils of Kharagpur, West Bengal, India, during spring–summer (February-June) seasons for three years (2015–2017) to evaluate okra crop response under subsurface drip and conventional furrow irrigation with varying amount of nitrogen treatments. Irrigation treatments had three levels of soil water depletion from field capacity (i.e., 20%, 35%, and 50%) under subsurface drip system. There was no soil water depletion under conventional furrow irrigation system. There were four levels of nitrogen fertilizer treatments (i.e., 0, 80, 100, and 120 kg ha−1). This was supplied using urea as a nitrogenous fertilizer. The yield response of okra crop under subsurface drip was found to be 56.4% higher than that of the furrow irrigation treatment. Best yield response and maximum water use efficiency and nitrogen use efficiency were recorded under 20% soil water depletion with 100 kg ha−1 of nitrogen fertigation. Among the various soil moisture depletions, subsurface drip at 20% soil water depletion treatment responded least quantity of water lost through deep drainage and nitrogen loss beyond the root zone as compared to other irrigation treatments. The water loss through subsurface drainage was observed as 33.11 mm lesser under subsurface drip as compared to that of the furrow irrigation, and this may due to low-volume and frequent irrigation water application with subsurface drip. Hence, irrigation through subsurface drip should be used for improving water and nitrogen fertilizer use efficiency of okra crop cultivation.

Modeling Moisture Flow in Root Zone: Identification of Soil Hydraulic and Root Water Uptake Parameters

AbstractThe present study is concerned with the analysis of moisture flow in the crop root zone and estimation of soil hydraulic and root water uptake parameters from soil moisture depletion data u...

Effects of land use changes for ecological restoration on soil moisture on the Chinese Loess Plateau: a meta-analytical approach

Soil moisture is an important resource for plant growth on the arid and semi-arid Loess Plateau of China where the “Grain for Green” project was launched in 1999, but there has been no systematic evaluation of soil moisture from the effects of ecological restoration at a regional scale. We systematically assessed 63 published studies during 2000–2015, including 2050 observations at 68 sites on the Loess Plateau with the aim of determining soil moisture changes and the factors influencing those changes. We found that, after land use conversion, soil moisture decreased by 17% in the upper 100 cm soil layer and that tree plantations and shrub lands appeared to cause soil moisture depletion which became increasingly serious with soil depth. The decrease of soil moisture was significantly influenced by the planting species in all restoration types (tree plantations, shrub lands, and grasslands). We also found that tree plantations and grasslands converted from farmlands consumed more soil moisture than from wasteland (including bare land, abandoned land and wild grasslands). Artificial restoration led to significant soil moisture reduction, but natural restoration had little effect on soil moisture. Therefore, natural restoration should be an alternative restoration practice on the Loess Plateau. These results will provide helpful information for artificial afforestation and planning ecological restoration campaigns for policy makers on water-limited regions.

The effect of stump removal and tree admixture on butt decay incidence, damage and wood density in western redcedar

Western redcedar (WRC) trees of 48–49 years in age grown in monoculture and in admixtures with birch, Douglas-fir and pine in the interior of British Columbia were sampled for wood density and the presence and level of damage from butt decay initiated by Armillaria ostoyae in stumped and unstumped plots. Stump removal reduced butt decay incidence in WRC from 18% to 2% and damage from 3.5% of the diameter at base to 0.3% compared to when stumps remained. External lesions on tree bases caused by Armillaria root disease increased the probability of WRC stems having butt decay by 1.25 times for an average-sized lesion. The incidence of butt decay and the level of internal damage to WRC in sampled plots was not related to admixture, tree size or site index. Stump removal controlled the inoculum of Armillaria root disease, thereby reducing incidence and size of WRC basal lesions that probably act as infection courts for other fungi causing butt decay. WRC trees grown in monoculture or with birch had the highest wood densities of all planting mixes tested. Wood density in WRC was lowest at the outer edges of individual WRC trees, in larger trees, and in plots where stumps had not been removed. The lower density WRC wood is thought to occur by overtopping from fast-growing species in admixture and depletion of soil moisture affecting latewood formation. This is a first report of stump removal affecting butt decay and admixture affecting wood density in WRC.

The Impact of Drought on Native Southern California Vegetation: Remote Sensing Analysis Using MODIS‐Derived Time Series

AbstractEcosystems in Mediterranean climates are adapted to seasonal drought. Multiannual drought, however, may significantly affect Mediterranean ecosystems and, further, may affect their constituent communities in different ways with differences in responses emerging during severe drought and over the course of long‐term climate change. This study investigates the response to recent prolonged drought of two important Mediterranean‐climate vegetation types: chaparral and coastal sage scrub. Their greenness was monitored from 2000 to 2017 using the Normalized Difference Vegetation Index (NDVI) derived from the Moderate Resolution Imaging Spectroradiometer. A bootstrapped multiple regression of NDVI anomalies against Palmer Drought Severity Index was used to assess the response of vegetation to drought. The results suggest that drought had a greater effect on chaparral‐dominated ecosystems than coastal sage over the entire region. Shallow‐rooted coastal sage scrub displayed higher interannual variability in NDVI than chaparral but had a lower correlation with Palmer Drought Severity Index. This suggests that this vegetation community is generally less responsive to drought on longer timescales than chaparral, which may be more sensitive to soil water depletion in a prolonged drought. Soil texture plays a critical role in affecting the community sensitivity to drought. For chaparral communities, elevation is negatively correlated with drought sensitivity, suggesting the role of temperature‐related water stress on their long‐term response to drought. Future predicted climate change in the form of increased temperature and drought hazards in Southern California will influence the native ecosystems in nonuniform ways. Long‐term trends in soil moisture depletion and temperature may be particularly important in chaparral‐dominated areas.

Vegetation Control and Soil Moisture Depletion Related to Herbicide Treatments on Forest Plantations in Northeastern Oregon

AbstractReforestation in the Inland Northwest, including northeastern Oregon, USA, is often limited by a dry climate and soil moisture availability during the summer months. Reduction of competing vegetative cover in forest plantations is a common method for retaining available soil moisture. Several spring and summer site preparation (applied prior to planting) herbicide treatments were evaluated to determine their efficacy in reducing competing cover, thus retaining soil moisture, on three sites in northeastern Oregon. Results varied by site, year, and season of application. In general, sulfometuron (0.14 kg ai ha–1 alone and in various mixtures), imazapyr (0.42 ae kg ha–1), and hexazinone (1.68 kg ai ha–1) resulted in 3 to 17% cover of forbs and grasses in the first-year when applied in spring. Sulfometuron+glyphosate (2.2 kg ha–1) consistently reduced grasses and forbs for the first year when applied in summer, but forbs recovered in the second year on two of three sites. Aminopyralid (0.12 kg ae ha–1)+sulfometuron applied in summer also led to comparable control of forb cover. In the second year after treatment, forb cover in treated plots was similar to levels in nontreated plots, and some species of forbs had increased relative to nontreated plots. Imazapyr (0.21 and 0.42 kg ha–1) at either rate, spring or summer 2007, or at lower rate (0.14 kg ha–1) with glyphosate in summer, provided the best control of shrubs, of which snowberry was the dominant species. Total vegetative cover was similar across all treatments seven and eight years after application, and differences in vegetation were related to site rather than treatment. In the first year after treatment, rates of soil moisture depletion in the 0- to 23-cm depth were correlated with vegetative cover, particularly late season soil moisture, suggesting increased water availability for tree seedling growth.

Performance of Turmeric and Soil Moisture Depletion Pattern Under Different Water Regimes and Nutrient Sources at New Alluvial Zone of Indo-Gangetic Plains, India

ABSTRACTIn India, the production of turmeric is not even half compared to its potential. To analyze the possibilities for higher production in turmeric, this study was conducted at the BCKV, Gayeshpur, West Bengal, during 2011 and 2012, to evaluate the effect of irrigation scheduling (0.6, 0.9, and 1.2 irrigation water (IW)/cumulative pan evaporation (CPE) and rainfed) in main plots and nutrient management [100% inorganic, 75% inorganic + 25% FYM (Farm yard manure), and 50% inorganic + 25% FYM + 25% vermicompost] in subplots on soil moisture depletion and productivity of turmeric. The highest value of fresh rhizome yield (23.90 kg ha−1) and qualitative indices were obtained with irrigation schedule at 0.9 IW/CPE ratio water regimes and 50% inorganic + 25% FYM + 25% vermicompost. The correlation coefficients of water use and yield of turmeric were found at 0.943. The combination of 0.9 IW/CPE and 50% inorganic + 25% FYM + 25% vermicompost improved the overall performance of turmeric crop.

Variations in quality constituents of green tea leaves in response to drought stress under south Indian condition

Abstract Soil moisture stress seriously limits the growth and development of tea plants (Camellia sinensis), thus affecting crop yield and quality. Soil moisture reduction generally affects accumulation of tea secondary metabolites. To elucidate the variations in plant genotype response to abiotic stress during depleting soil moisture stress and changes in biochemical constituents of green leaf which determines the quality of black tea was investigated. An experiment was conducted at UPASI Tea Research Foundation Tea Research Institute, Distinctiveness-Uniformity-Stability center with drought tolerant clones namely UPASI-2, UPASI-6, UPASI-9, ATK-1, TRI-2025 and drought susceptible clones UPASI-3, UPASI-8, UPASI-17, TRF-1 of same age. Green leaves were collected from each plot was subjected to HPLC analysis for dihydroxyflavan-3-ols, trihydroxyflavon-3-ols and caffeine, and the results were statistically analyzed. The study indicated that the levels of total polyphenols, individual catechins, reducing sugars, amino acids and total lipids were significantly different at P ≤ .05 among the treatments. Caffeine level increased (P ≤ .05) with decrease in soil moisture for all the clones. Principal component analysis and hierarchical cluster analysis revealed differences between tea cultivars with respect to their quality and tolerance. Our study further indicated that the tolerant clones were able to accumulate higher levels of bio constituents during soil moisture stress than the susceptible ones. Quality of green tea leaf precursors is directly influenced by the soil moisture availability and is varietal dependent. This could be an important tool for the assessment of clonal performance and drought tolerance in tea cultivars.

Water productivity for Egyptian clover as affected by different irrigation regimes and cultivation methods in the North Middle Nile Delta Region

A FIELD experiment was conducted in the two successive winter seasons ( 2016-17 and 2017-18) to investigate the impact of cultivation method; dry cultivation ( dry seed on dry soil) and traditional one (wet seed on wet soil) and irrigation regime; five different irrigation regimes as follows, irrigation till 5 cm above soil surface, (traditional, I1), using soil moisture depletion (I2), irrigation with 0.8 from pan evaporation (I3), irrigation with Hargreaves equation, 1981 (I4) and irrigation till 2.5 cm above soil surface (I5).The obtained results showed that decreasing amount of irrigation water from traditional method (I1) to 2.5 cm above soil surface (I5) reduced fresh yield by 5.49 and 6.75 ton fed.-1 with water saving ≈14.5% (≈ 336.0 m3fed.-1,) for dry seeds cultivation method, and the corresponding values 4.87 and 7.34 ton fed.-1 with water saving 10.75% (≈ 280.0 m3fed.-1,) for wet cultivation one in the overall seasons. Meaningfully, an average of ≈ 700-840 million m3 water could be saved at the national level (≈2.5 million fed.). Moreover, mean reduction in dry yield by 24.62 kg fed.-1, (6.35 %) and 13.00 kg fed-1 (3.51 %) could be resulted from dry cultivation method, and by 36.45 kg fed-1 (8.68 %) and 10.91 kg fed-1 (2.60 %) could be resulted from wet cultivation method in the first and second seasons respectively.The highest overall mean values of water consumptive use (CU) and consumptive use efficiency (Ecu, %) were recorded irrigation without any stress during the growing season (I1). Productivity of irrigation water (PIW kgm-3) and water productivity (WP kgm-3) for fresh yield was the highest values recorded under I5 (the lowest water consumed) for dry and wet cultivation methods.

The high‐impact 2007 hot summer over Turkey: atmospheric‐blocking and heat‐wave episodes

ABSTRACTThe 2007 summer was extraordinary in the Balkans and Turkey, with the region experiencing a very hot summer in numerous places, setting all‐time maximum temperature records and suffering destructive fires. The heat wave exhibited daily maximum temperature anomalies in excess of 14 °C in some cities. These high‐temperature anomalies can be related to a number of concurrent atmospheric and physical factors that induce persistent anticyclones, sea‐surface temperature anomalies, reduced precipitation and depleted soil moisture. Prominent atmospheric factors conducive to heat‐wave events can serve as a dynamic fingerprint and yield insight into their most important triggering and driving mechanisms. The prolonged atmospheric‐blocking high meandering over the central Mediterranean orchestrated the atmospheric circulation and led to the advection of warm air from North Africa to the Balkans and Turkey. The associated large‐scale subsidence and clear‐sky conditions resulted in temperatures surpassing 40 °C at many places. Atmospheric and physical conditions contributed positively to the very high temperatures and led to two major heat‐wave episodes in June and July. Atmospheric‐blocking analysis revealed that two blocking episodes accompanied these heat waves. Results from this analysis indicate that the atmospheric blocking was likely responsible for establishing and maintaining the hot‐weather conditions. The summer of 2007 may be considered as a strong indicator of what Turkish summers may become in future.

Yield and Some Water Relation of wheat (Triticum aestivum L.) Crop as Influenced by Irrigation Regime, Nitrogen Fertilization Rates and Dosses at North Nile Delta.

Two field experiments were carried out at Sakha Agricultural Research Station, Kafr El-Sheikh Governorate, Egypt during the two successive seasons of 2014/2015 and 2015/2016. The objectives of this research were: (i) to study the effect of irrigation regime using tow irrigation levels (40% and 60%) of soil moisture depletion on wheat grain yield; (ii) to evaluate the growth, yield and N use efficiency of wheat as affected by different rates of N fertilization. The experimental used design was split split plot design with three replicates. Irrigation regimes I1 (irrigated at 40% depletion) and I2 irrigated at 60% depletion were assigned in the main plots. Three nitrogen rates i.e. zero, 50, and 75 kg N fed-1 in the sub plots namely N0, N50, and N75 and two doses of nitrogen i.e D1 one time and D2 tow times Results showed that irrigation at 40% depletion significantly increased grain yield by 6.03, 5.5% and straw yield by 7.8, 9.1% compared to irrigation at 60% depletion during the tow growing seasons respectively. The highest grain yield value of 3107.43, 2955.50 kg fed-1 was obtained with I1N75D2 treatment, while the lowest one was 2265.05, 2174.05 kg fed-1 with I2N50D1­ in the 1st and 2nd seasons respectively. Also irrigation at 40% depletion resulted in the higher amount of irrigation water to be 1810, 1920 m3 fed-1 distributed on 5 irrigations while it was 1460, 1600 m3 fed-1 irrigated at 60% depletion distributed on 4 irrigations during the 1st and 2nd seasons respectively. The highest consumptive water use was obtained under irrigation at 40% depletion i.e 38.53, 39.6 cm while the lowest 32.48, 32.58 cm obtained from irrigation at 60% depletion in the 1st and 2nd seasons respectively. Increasing nitrogen rates up to 75 kg N fed-1 (N75) significantly increased grain yield by 234.4%, 119.0% and 218.5%, 111.2 % as compared to control N0; N50 treatments in the 1st and 2nd seasons respectively. Also, increased straw yield by 192.9%, 111.4% and 182.4%, 111.6% as compared to N0; N50 treatments in the 1st and 2nd seasons respectively. Nitrogen use efficiency (NUE) increased with increasing water applied. It was 0, 42.07, 24.23 and 0, 31.74, 17.32 for N0, N50 and N75 on the 1st and 2nd seasons respectively, results showed that increasing the applied N-rate decrease the NUE since the highest value was obtained with N50 and the lowest one obtained with N75. The highest water productivity (WP) of 2.20, 2.4 kg m-3 was obtained with I2N75D2 treatment during 1st and 2nd seasons respectively. Therefore, it could be recommended that irrigate wheat at 60% depletion in north Nile Delta soils to save water of about 320 m3

Root-Zone Soil Water Balance and Sunflower Yield under Deficit Irrigated in Zambia

The study was conducted at the University of Zambia, Research Field Station, Lusaka, Zambia to evaluate the root zone soil water balance under full, and deficit irrigated sunflower. The specific objectives were: 1) to assess the sunflower growth and yield under varying irrigation water regimes; 2) to evaluate the root-zone water balance; and 3) to evaluate the water use efficiency of sunflower. Sunflower (Helianthus annuus, var Milika) was planted in a Randomized Complete Block Design (RCBD) with four irrigated water regimes in four replications. The treatments comprised: treatment (T1) = 30% ETc; treatment (T2) = 54% ETc; treatment (T3) = 65% ETc; and treatment (T4) = 100% ETc. The sunflower crop was irrigated on a weekly irrigation schedule using sprinklers. The measured parameters included: weather data, soil moisture profiles, growth stages (emergence, flowering, maturity), above-ground biomass, and grain yield. The results of the study showed that growth parameter (biomass and seed yield) decreased with a decrease in applied irrigation water. The sunflower seed yield varied from 0.22 to 1.40-ton&#183ha-1 with an average yield of 0.81-ton&#183ha-1. The highest grain yield was obtained under treatment (T4), and the least grain in yield harvest was at treatment (T1). The statistical analysis showed significant differences in seed yield among the treatments. The treatments (T1 and T2) were not significantly different (p > 0.05). These results showed that when water deficit was set at 65% and 100% ETc and uniformly distributed throughout the sunflower growth, there were no significant differences in biomass, stover and seed yield. In literature, the allowable soil moisture depletion factor for irrigation scheduling of sunflower is set at 45%. The yield components decreased as irrigation levels decreased for each irrigation interval. The 65% ETc treatment could be recommended for sunflower irrigated in semi-arid regions and be used as a good basis for improved irrigation strategy development under water stressed environment.

Determination of Crop Water Requirements for Maize in Abshege Woreda, Gurage Zone, Ethiopia

In Ethiopia where crop production overly depends on rainfall and temperature, studying the variability of these climate variables at a local scale is essential to devise proper strategies that enhance adaptive capacity. In light of this, a study was conducted in Abshege Woreda, Gurage Zone to determine crop water requirement of maize, which is major food crop of the area. Ten years i.e., (2006-2015) Indibir station climatological records of (sunshine duration hr/day), maximum and minimum temperature (OC), humidity (%) and wind speed (km/day) at 2 meters height were used in FAO Penman Monteith method. Secondary data were used to collect important soil parameters required for determination of crop water requirement in the study area such as field capacity (FC), permanent wilting point (PWP), initial soil moisture depletion (as % TAM) and available water holding capacity (mm/meter) while data for maximum rain infiltration rates (mm/day) and maximum rooting depth (cm) were obtained from literature based on similar textural class of the soil in the study area. Lengths of total growing periods of the crop was determined from ten years climate data and planting date was 10th May acquired from OAWBA and farmers of the area. Crop coefficients (kc), rooting depth, depletion level and other agronomic parameters were obtained from FAO guidelines (No 56) for each growth stage. The analyzed data indicated that Crop water requirement was estimated using CROPWAT 8.0 for window. A maize variety with a growing period of 140 days to maturity would requires 423 mm depth of water, while 101 mm would be required as supplementary irrigation depth.

Influence of rice (Oryza sativa) habit groups and moisture conservation practices on soil physical and microbial properties in rice + lathyrus relay cropping system under rice fallows in Eastern Plateau of India

The study involving bio-physical aspects of popular rice (Oryza sativa L.) + lathyrus relay system for conserving natural resources and deriving the best benefits out of them was carried out in a vertisols at Indira Gandhi Krishi Vishwa Vidyalaya, Raipur (India) during 2011-14. The study location comes under tropical sub humid climate that receives an annual precipitation of 1582 mm. Two rice habit groups (a tall local rice Masuri maturing at 140 days visà -vis a dwarf HYV of rice Swarna with 110 days duration) were combined with two moisture conservation practices (retaining rice stubble height up to 15 cm versus 30 cm) for growing two contrasting varieties of lathyrus (early high biomass accumulating Ratan vis-à -vis medium high biomass Prateek). The study showed that soil moisture depletion pattern was relatively lower in case of residue retention at a higher cutting height, i.e. 30 cm in comparison to 15 cm with better and higher crop cover in the former. At later stages of lathyrus, faster moisture depletion was observed in case of lathyrus Ratan over that in Prateek. Yet, maximum soil moisture depletion was recorded under Prateekespecially under long rice habit group since it stayed for long as compared to ‘Ratan’. Similarly, bulk density (BD) was increased slightly with both time and soil compaction as a result of tillage or soil traffic. Soil strength indicated higher order variation (0.13 to 0.19) which could explain relatively higher sensitivity of soil strength to relay cropping situation in comparison to BD. However, marginal changes did occur in respect of soil porosity (47- 50%), pH (6.6 to 7.2) and EC (0.12 to 0.14 dS/m) at 15 cm profile depth. Moreover, as a result of slow depletion of soil moisture storage (SMS) following stubble retained at 30 cm height, soil organic carbon (SOC) status was greatly enhanced under it. Similar small increments in respect of soil fertility attributes such as soil available N (193.4 to 210.4 kg/ha), soil-P (10.3 to 12.2 kg/ha), soil-K (465.4 to 475.4 kg/ha), Cu (2.2 to 2.5 mg/kg), Fe (6.9-7.6 mg/kg), Zn (0.69-0.84 mg/kg) and Mn (6.2-6.9 mg/kg) after the harvest of rice were observed with diverse treatment combinations. Similarly, soil microbiological properties such as Rhizobium, dehydrogenase activity, crop growth and nodulationdid affect following treatment imposition. Besides these, weed dynamics and the resultant yield attributes and grain yield were favoured especially in those treatments where soil moisture is conserved (higher SMS) and availability of it was extended over a period of time. Therefore, the study carried out in a lentil relayed with diverse rice habits showed that efficient management of soil and land resources was crucial for realizing higher output through adequate soil cover with better soil health.

IMPROVE WATER PRODUCTIVITY OF WHEAT IN SHALLOW WATER TABLE AREA IN THE NORTH NILE DELTA, EGYPT

Two field experiments were established in 2014/2015 and 2015/2016 winter seasons at Sakha Agriculture Research Station (31° 07' N latitude, 30° 05' E longitude), North Nile Delta, Egypt. Objective of the investigation is to improve productivity of water and wheat yield in shallow water table area. Irrigation scheduling treatments were assigned in the main plot, fertilizer levels were allocated in the sub-plots. While microorganisms treatments were allocated in sub sub-plots. Irrigation scheduling was done at 50%±5 (I1), irrigation at 70% ±5 (I2) and irrigation at 90%±5 (I3) of available soil moisture depletion (ASMD). Treatments of nitrogen fertilizer were 75% (F1) and 100% (F2) of the recommended nitrogen fertilizer. The plant growth promoting rhizobacteria treatments (PGPR) were cyanobacteria (Cy), Rhizobium (R) and consortium cyanobacteria and Rhizobium (Cy +R) as well as the control treatment without inoculation (C). Results revealed that there are no significant differences in grain yield, harvest index, number of spikes m-2 and weight of 1000 grains between I1 and I2. Grain yield under I3 decreased by 11% and 8% compared to I1 and I2 respectively over both growing seasons. The values of wheat consumptive use and irrigation water applied has the descending order I1 > I2 > I3 over both growing seasons. The seasonal water consumptive use was 30.22, 26.25, and 22.81 cm for I1, I2 and I3 respectively. Irrigation water applied was 39.02cm, distributed on five irrigations, 32.43 cm, distributed on four irrigations, and 27.36 cm distributed on three irrigations including seedling irrigation for I1, I2 and I3 respectively. Total seasonal water requirement was 50.0, 47.38 and 45.75 cm for I1, I2 and I3 respectively over both seasons. Mean percentage of groundwater contribution has the descending order I3> I2 > I1 to be 46%, 26.9% and 10.2% for I3, I2 and I1 respectively over both seasons. So, when water becomes a limiting factor for wheat productivity in such area, farmers can apply I3 with F1 and Cy +R because it increased productivity of irrigation water (PIW) and water productivity (WP) by 37% and 79% respectively, as well as saved nitrogen fertilizer and irrigation water by 25% and 30% respectively compared to I1 with F2 and C.