Total Amount Of Irrigation Water Research Articles

The Influence of Sprinkler and Drip Irrigation on the Incidence and Severity of Bacterial Disease in Onions Grown in Northeast California

Overhead sprinkler irrigation and its effect on leaf wetness are often referenced as a key factor for bacterial disease spread in onions grown in arid climates. A study was conducted in 2021 and 2022 in Tulelake, California, to compare the incidence and severity of bacterial disease under sprinkler and drip irrigation. The experiment was a split-plot randomized complete block design with drip and solid-set sprinkler irrigation as the main plot treatments and inoculation and no inoculation with plant-pathogenic bacteria as the split-plot treatments. The entire study area was irrigated with solid-set sprinklers from planting until the five-leaf stage to facilitate uniform onion germination and chemigation of herbicides for weed control. After the five-leaf stage, irrigation treatments were imposed for the remainder of the growing season. Total irrigation water amount and irrigation frequency were similar for both irrigation methods. Foliar disease severity and the incidence of bulb rot were 170 and 186% higher, respectively, for solid-set sprinkler compared with drip irrigation. Leaf wetness within the plant canopy during onion bulbing was on average 36% higher in the solid-set sprinkler compared with drip irrigation treatment, whereas relative humidity and temperature were similar between irrigation methods. Drip irrigation maintained lower soil water tension and increased average bulb size by 9% compared with solid-set sprinkler irrigation. This study confirms historical observations that overhead irrigation can extend leaf wetness and increase bacterial disease in onions in arid production areas and highlights the potential benefits of the adoption of drip irrigation.

Improving Wheat Yield and Water-Use Efficiency by Optimizing Irrigations in Northern China

Achieving the goal of increasing both crop yield and water-use efficiency with a better irrigation regime is a major challenge in semi-arid areas. In this study, we presented a two-season field experiment (October 2018–June 2019 and October 2019–June 2020) that considered drought stresses, i.e., no irrigation (W0), irrigated in jointing (W1), both in jointing and flowering (W2) after re-greening, and wheat varieties (S086; J22). The results showed that a 45.5% excess of irrigation water input did not promote wheat yield (W1 vs. W2). S086 was beneficial for the usage of soil water consumption under a low amount of irrigation water in both seasons. In addition, irrigation positively affected the activities of superoxide dismutase and catalase in flag leaves (p < 0.05). A decrease in irrigation helped to increase the concentrations of soluble sugar and proline and decrease the amount of malondialdehyde content for S086. For the water- and irrigation-water-use efficiency, W1 was significantly increased by 20.6–21.7% and 38.3–39.3% in 2018–2019 and 23.4–24.4% and 43.8–44.7% in 2019–2020, respectively, as compared to W2. Additionally, a higher yield for S086 than J22 was found under deficit irrigation. Consequently, our study suggested that the S086 variety combined with a total amount of irrigation water of 165 mm might be recommended to meet the win–win goal of high crop yields and water-use efficiency for reducing ground water depletion in the future.

Effects of Temperature and Irrigation Intervals on Photosynthesis, Growth and Growth Analysis of Pot-grown Cucumber Seedlings

This study was conducted in an indoor cultivation room and chamber where environmental control is possible to investigate the effect of temperature and irrigation interval on photosynthesis, growth and growth analysis of potted seedling cucumber. The light intensity (70 W·m-2) and humidity (65%) were set to be the same. The experimental treatments were six combinations of three different temperatures, 15/10℃, 25/20℃, and 35/25°C, and two irrigation intervals, 100 mL per day (S) and 200 mL every 2 days (L). The treatments were named 15S, 15L, 25S, 25L, 35S, and 35L. Seedlings at 0.5 cm in height were planted in pots (volume:1 L) filled with sandy loam and treated for 21 days. Photosynthesis, transpiration rate and stomatal conductance at 14 days after treatment were highest in 25S. These were higher in S treatments with a shorter irrigation interval than L treatments. Total amount of irrigation water was supplied evenly at 2 L, but the soil moisture content was highest at 15S and lowest at 25S > 15L > 25L, 35S and 35L in that order. Humidity showed a similar trend at 15/10℃ (61.1%) and 25/20℃ (67.2%), but it was as high at 35/25°C (80.5%). Cucumber growth (plant height, leaf length, leaf width, chlorophyll content, leaf area, fresh weight and dry weight) on day 21 was the highest in 25S. Growth parameters were higher in S with shorter irrigation intervals. Yellow symptom of leaf was occurred in 89.9% at 35S and 35L, where the temperature was high. Relative growth rate (RGR) and specific leaf weight (SLA) were high at 25/20℃ (25S, 25L), RGR tended to be high in the S treatment, and SLA in the L treatment. Water use efficiency (WUE) was high in the order of 25S, 25L > 15S > 15L, 35S, and 35L. As a result of the above, the growth and WUE were high at the temperature of 25/20℃.

MINIMIZATION OF WATER NEEDS IN IRAQI AGRICULTURE IN LIGHT OF THE PREVAILING CROPPING COMBINATION DURING

The research aims to study the optimal allocation of irrigation water that is used to irrigate various agricultural crops at the level of Iraq. In order to achieve the goal of the research, two economic models were formulated according to the linear programming technique. The first model aimed to minimize the water needs of the prevailing crop combination during the average period (2017-2020), while the second model aimed to maximize the total profit margin of the water unit for the crop combination that minimizes the water needs during the same period. The first model was estimated with two proposed plans. The first proposed plan included non-imposing legislative restrictions related to the allocation of certain areas for basic agricultural crops that bias the food security requirements of the population, as well as crops that were recently banned from import by the Iraqi government, while the proposed second plan included the imposition and addition of restrictions of legislative areas that did not appear in the table of the optimal solution for the first plan. Results indicated that there is a surplus of water resource for the proposed economic plans according to the two estimated models, its quantity amounted to about 363.361, 9.178 million m3 for each plan, respectively, compared to the total amount of irrigation water needed for the current cropping combination, which was estimated at about 4.736726 billion m3 during the average mentioned period. Results of the analysis of the two estimated models also showed a preference for the results of plans with legislative restrictions as a result of the expansion in the cultivation of most basic and important crops and vegetables for local consumption.

Model-Based Approach for Treated Wastewater Reuse Strategies Focusing on Water and Its Nitrogen Content “A Case Study for Olive Growing Farms in Peri-Urban Areas of Sousse, Tunisia”

One of Tunisia’s main challenges is to conserve and protect water resources for current and future generations. Using non-conventional water in agriculture, such as treated wastewater, can be a sustainable water-saving solution. Therefore, the objectives of this study are (i) to analyze the value chain of treated wastewater for olive growing farms production and (ii) to apply mathematical modeling to maximize the olive production in optimizing irrigation distribution and nitrogen amendment in olive growing farms. The work is carried out in a peri-urban irrigated perimeter of Msaken, Sousse, which is mainly occupied by olive trees and irrigated by treated wastewater. A SWOT analysis is also applied to identify the strengths and weaknesses of reuse in this study area. Moreover, mathematical models are used to determine the optimal schedule for fertigation with treated wastewater. In this process, data on rainfall, soil, water quality and olive production were collected from local farmers, local decision makers, field and laboratory experiments. SWOT results determine farmers’ perceptions of reusing treated wastewater for irrigation. The viability analysis, in terms of soil humidity and nitrogen, shows that the nitrogen stress is not a limiting factor for olive biomass production, but water stress is. This analysis provides numerical values for the maximum irrigation rate and total amount of irrigation water to ensure maximum olive production. It was found that the maximum irrigation could be 5.77 m3/day/ha and the total annual water requirement is 1240 m3/ha. Modeling appears to be an important tool to help local decision makers and to support and encourage local farmers to reuse treated wastewater under safe conditions and without environmental risks.

Assessing the maximum potential cooling benefits of irrigation in Australia during the “Angry Summer” of 2012/2013

Recent studies using global climate models have suggested that irrigation, assuming unlimited water supply and that all crops can be irrigated, may be an option for regional cooling in southeast Australia. In this paper, using idealised simulations, we aim to quantify the maximum possible benefits of irrigation in southeast Australia during a record breaking summer. By limiting the amount of irrigation applied to the actual amount used, and only to areas which are equipped for it, our study provides much needed practical context on the maximum potential benefits of irrigation for southeast Australia. We conduct simulations with the Weather Research and Forecasting regional atmospheric model to investigate the sensitivity to both land surface models and irrigation parameters (start hour, duration and frequency). All simulations used the same total amount of irrigation water. Our results show that irrigation could potentially reduce the mean seasonal maximum temperature during the Angry summer of 2012/2013 by −1.44°C to −2.13°C over irrigated regions. Maximum possible cooling was achieved by applying irrigation during the middle of the day, over 4 h, with daily application. During early hours of the morning, increasing the number of hours that irrigation is on has little to no effect on maximum cooling, but longer duration of irrigation later during the day leads to larger cooling. Similar results were found when decreasing irrigation frequency. The amount of cooling was strongly dependent on the land surface model, with use of the CLM model resulting in 2.32 to 2.66 times more cooling as compared to the Noah and Noah-MP land surface models, highlighting the importance of using multiple land surface models. Our results also highlight that considering realistic irrigation volumes and equipped-areas leads to cooling benefits that are largely local, and studies using global models that do not take this into consideration are likely over-estimating the potential cooling benefits of irrigation.

Rice yield, water productivity, and nitrogen use efficiency responses to nitrogen management strategies under supplementary irrigation for rain-fed rice cultivation

Rainfall-adapted irrigation (RAI) or supplementary irrigation for rain-fed rice cultivation consumes less amount of irrigation water by harvesting rainfall and thus is vital for sustainable rice (Oryza sativa L.) production in multi-rain areas, including the Jianghan Plain in China. However, nitrogen management strategies influence rice growth and water and nitrogen utilization under RAI remains unclear. Thus, we conducted a two-year (2016 and 2017) field experiment at Jingzhou City, central China to investigate the effects of nitrogen management strategies on grain yield, crop water productivity (CWP), and nitrogen use efficiency (NUE) of rice under conventional flooding irrigation (CF) and RAI. The nitrogen management strategies included local farmers’ nitrogen fertilization (CN), common urea (30% nitrogen) blended with controlled-release nitrogen fertilizer (70% nitrogen) (U+CRF), and optimized nitrogen fertilization (ON), at a nitrogen rate of 180, 180, and 150 kg ha−1, respectively. Compared to the CF condition, RAI down-regulated the numbers of irrigation (−3 in 2016 and −4 in 2017) and reduced the total amount of irrigation water (−41.6% in 2016 and −45.6% in 2017), suggesting that rainfall-adapted irrigation enhanced the rainwater storage capacity and usage. RAI also increased root length, root and shoot biomass, net photosynthetic rate, crop growth rate, nitrogen accumulation, percentage of productive tillers, harvest index, and nitrogen harvest index. The U+CRF and ON increased or maintained these parameters compared with the CN. Compared to the traditional irrigation and nitrogen fertilization pattern (CF interacted with CN), RAI combined with U+CRF or ON enhanced root length and root biomass, and had a relatively high spikelets number per panicle, grains filled percentage, and 1000-grain weight, and thus produced a high grain yield. Moreover, the new treatment reduced amount of irrigation water and improved utilization of nitrogen fertilizer, resulting in a greater CWP and NUE. The enhanced grain yield, CWP, and NUE were associated with the increased root biomass and root length. Therefore, rainfall-adapted irrigation combined with the new nitrogen management (U+CRF or ON) can synergistically increase grain yield and resource use efficiency by improving root growth in rice.

Response of Lactuva Sativa Var. Crispa to deficit irrigation and leonardite treatments

In this study, effects of deficit irrigations and leonardite treatments on water use efficiency (WUE), water consumption and agricultural productivity of Lactuva Sativa Var. Crispa were examined in a pot experiment under greenhouse conditions. Experimental treatments included: L0: (Control), L5: (5% leonardite + 95% soil), L10: (10% leonardite + 90% soil) and L20: (20% leonardite + 80% soil) with I100 (full irrigation, control) and I80 and I60 (deficit irrigation). Plant water depletions were determined by weighing the pots. The highest total amount of irrigation water (9.74 × 10−3 m3/pots) was observed in L0I100 control treatment and the lowest value (5.52 × 10−3 m3/pots) was obtained from L20I60 treatment. The highest WUE (41.63 kg/m3) was obtained from L10I80 treatment. The greatest yield (139 g), plant length (20.14 cm) and number of leaves per plant (28) were respectively obtained from L0I100 treatments. The greatest plant diameter (37.05 cm) was obtained from L10I100 treatment. Present findings revealed that L0I100 treatments were prominent for yield and L10I80 treatments for WUE and plant nutrient uptake. Lactuva Sativa Var. Crispa exhibited a strong dependence on water; yield and growth parameters were adversely influenced from I60 deficit irrigation treatments. Additionally, plant water consumptions decreased with Leonardite treatments.

Numerical simulation on effect of irrigation conditions on water temperature distribution in a paddy field

Water management methods regulate water temperature in paddy fields, which affects rice growth and the environment. To understand the effect of irrigation conditions on water temperature in a paddy field, water temperature distribution under 42 different irrigation models including the use of ICT water management, which enables remote and automatic irrigation, was simulated using a physical model of heat balance. The following results were obtained: (1) Irrigation water temperature had a more significant effect on paddy water temperature close to the inlet. As the distance from the inlet increased, the water temperature converged to an equilibrium, which was determined by meteorological conditions and changes in water depth. (2) Increasing the irrigation rate with higher irrigation water amount increased the extent and magnitude of the effects of the irrigation water temperature. (3) When total irrigation water amount was the same, increasing the irrigation rate decreased the time-averaged temperature gradient effect over time across the paddy field. (4) Irrigation during the lowest and highest paddy water temperatures effectively decreased and increased the equilibrium water temperature, respectively. The results indicate that irrigation management can be used to alter and control water temperature in paddy fields, and showed the potential of ICT water management in enhancing the effect of water management in paddy fields. Our results demonstrated that a numerical simulation using a physical model for water temperature distribution is useful for revealing effective water management techniques under various irrigation methods and meteorological conditions.

Analyzing the Effectiveness of Modern Irrigation Methods in Iraq

Iraq is one of the countries that have water scarcity problem. Many reasons have made this problem to be more complex. The modern irrigation methods have used as one solution to the water problem in Iraq. This paper investigates the effectiveness of modern irrigation methods in Iraq. The paper tests the impact of using modern irrigation methods on the amount of water used for irrigation. The study uses Liner Regression Model (LRM) as a statistical estimation model. The study data were taken from the ministry of water resources, and the ministry of agriculture in Iraq. This study uses weekly time series data from 2000 -2010. The results show that using modern irrigation methods in Iraq has negative and insignificant impact on the total amount of irrigation water. The results shows that temperature (climate effect) has positive and significant impact on total irrigation water. The results shows that stored water has positive and significant impact on irrigation water.

Behavior of some Micronutrients and Water Productivity in Rice Soil Under Irrigation Intervals and Organic and Inorganic Fertilizes

A field experiment was carried out to investigate the effect of organic and inorganic fertilizers and their combinations under different irrigation intervals on yield and its attributes of the Giza178 rice cultivar, as well as, the availability of some micronutrients in the soil. Irrigation treatments were continuous flooding (CF), continuous saturation (CS), irrigation every 6 days (E6D), every 9 days (E9D) and every 12 days (E12D), while the fertilizer treatments were control (without fertilizer), 5t cattle manure ha-1 (CM), 5t compost ha-1 (C), 5t cattle manure +110 kg N ha-1 (CM+110N), 5t compost +110 kg N ha-1 (C+110N) and the recommended N rate of 165 kg N ha-1 (165N). Prolonged irrigation intervals of more than 6 days substantially decreased the yield and its attributes, Fe and Mn concentration in the soil in both seasons. The opposite was true for Zn concentration. Fertilizer sources containing chemical N (165N) alone or 110N with C or CM significantly surpassed each of the two organic sources alone in yield and yield attributes in the two seasons. The application of C+110N fertilizer with irrigation E6D was statistically at par with the recommended interaction (CF irrigation X 165N fertilizer) in yield and its attributes. The total amount of irrigation water applied was decreased by prolonging the irrigation interval. The inverse was true for water saved and water productivity in kg grains m-3. Application of C+110N fertilizer with irrigation E6D recorded the highest water productivity and saved water > 3000 m3 in the two seasons.

Evaluation of the irrigation schemes in the Antalya region

Bu çalışmada, Antalya bölgesinde bulunan 13 sulama şebekesi 2006-2016 yıllarına ait 11 yıllık veriler ile değerlendirilmiştir. Çalışmada su dağıtım, finansal ve tarımsal etkinlik göstergeleri kullanılmıştır. Sulama şebekelerinin performanslarının belirlenmesi ve karşılaştırılmasında korelasyon analizi, temel bileşenler analizi yapılmış ve sulama şebekelerinin kalite indeksleri belirlenmiştir. Yapılan performans değerlendirilmesinde her bir göstergeye ait 11 yıllık veri kullanılarak ortalama ve standart sapma değerleri hesaplanmıştır. Bu verilere göre sulama oranı en yüksek %82.21 ile Korkuteli sulamasında, birim sulanan alana dağıtılan toplam sulama suyu miktarı en düşük 5532.32 m3 ha-1 ile Mursal sulamasında bulunmuştur. Su temin oranı 3.74 ile en yüksek Alara sulamasında, fayda masraf oranı 0.76 olarak en düşük Manavgat sulamasında, birim sulanan alan üretim değeri 1855.53 $ ha-1 ile en yüksek Çıplaklı sulamasında gerçekleşmiştir. Birim şebekeye alınan sulama suyu üretim değeri en yüksek 2.90 $ m-3 ile Çıplaklı sulamasında hesaplanmıştır. Tüm performans göstergeleri faktör analizi kullanılarak tek bir sayıya (kalite indeksi değeri) indirgenmiştir. Bu indekse göre sulama şebekeleri, başarı sıralamasına tabi tutulmuştur. Yapılan kalite indeksi sıralamasında Korkuteli sulaması 1523.91 ile ilk sırada yer alırken Manavgat sulaması -514.38 ile son sırada yer almıştır. Araştırma sonucunda sulama şebekelerinin başarısına en fazla tarımsal etkinlik göstergelerinin etkili olduğu görülmüştür.

Su Hasadı Sistemlerinin Önemi ve Teknikleri

Dünyadaki en kritik yaşam unsurlarından biri olan suyun, etkili kullanımı gün geçtikçe önem kazanmaktadır. Nüfusun durmaksızın artması ve iklim değişiklikleri ile beraber; su kaynaklarının hem tüketim hızı hem de kullanım şekilleri tartışma konusu olmuştur. Bu konulara çözüm getirebilecek yöntemlerden biri de geçmişi çok uzun yıllar öncesine dayanan “Su Hasadı” yöntemidir. Su hasadı; insan, hayvan veya bitkilerin kullanımı için su sağlamak amacıyla, yağışla meydana gelen yüzey akışının toplanması olarak tanımlanabilir. Tekniğin mikro havza boyutunda çatı ve çiftlik sistemleriyle kullanımını görmek mümkünken; makro havza boyutunda ise vadi yatağı ve vadi dışı sistemler kullanılmaktadır. Su kaynaklarının önemli bir kısmını kullanan tarım sektöründe; üretimin devam ettiği kurak ve yarı kurak bölgelere düşen yağmur suyunun büyük bir kısmı, buharlaşma yoluyla veya akışa geçerek verimli bir şekilde kullanılamadan uzaklaşır. Su hasadı tekniğinde ise yağmur suları depolandıktan sonra tarım arazilerine uygulanmak üzere bekletilebilir. Yöntem; buharlaşma veya akış sebebiyle kayıplar yaşanmayacağından toplam sulama suyu miktarını arttıracak ve su kaynakları üzerindeki baskıyı azaltacaktır. Kaynakların yükünü azaltması dışında; toprak erozyonunun önlenmesinde oynadığı rol de yöntemin ana faydalarından biri olarak görülmektedir. Genel olarak uygun coğrafyaya göre uygun yöntem seçildiğinde; su hasadı düşük dış girdili bir yöntemdir ve uygulanması zor değildir. Birkaç istisna dışında, hasat edilen suyu iletmek veya uygulamak için enerjiye ihtiyaç duymaz. Bu çalışmada su hasadı yönteminin; ana unsurları, farklı kullanım alanları ve teknikleri hakkında bilgi verilmektedir.

Rice Irrigation Schedule Optimization Based on the AquaCrop Model: Study of the Longtouqiao Irrigation District

As a crop with high water consumption, rice is an important measure of efforts to improve agricultural irrigation efficiency and alleviate the contradiction between the supply and demand of agricultural water resources. This paper takes the Longtouqiao irrigation district, in the hinterland of the Sanjiang Plain, a major rice-producing area in northern China, as an example, and the AquaCrop crop growth model and entropy-cloud model are jointly used to develop a rice irrigation schedule optimization model based on three kinds of typical rainfall years. Different irrigation schemes are established and evaluated by using the model built based on images. The results showed that the yield’s normalized root mean square error (NRMSE) value of the AquaCrop model was 9.949% (< 10%) after calibration, and the our model results showed a good agreement with observed data, which indicated that the calibrated model was suitable for rice growth simulation in the research area. For the same irrigation water amount, rice was irrigated to a great extent at the tillering stage, and a small amount of irrigation water at the regreening stage of rice could improve rice yield. During irrigation, rice production can also be promoted by regulating the irrigation amount according to the rainfall in each growth period, and the optimal irrigation water amount can be controlled between 20 and 60 mm each time. Under the three typical annual scenarios of dry, normal and wet years, the respective optimal quantification results for the field capacity, total irrigation water amount and irrigation times in the rice growth period to attain the optimal irrigation effect were 25%, 425 mm, and 17 times, respectively; 25%, 450 mm, and 14 times; respectively, and 25%, 425 mm, and 17 times, respectively. The research results can provide a decision-making basis for water-saving measures and efficient rice irrigation water management.

Estimating Evaporation from Irrigation Canals in the Midstream Areas of the Heihe River Basin by a Double-Deck Surface Air Layer (DSAL) Model

Accurate quantification of evaporation loss from irrigation canals at an irrigation district scale is very useful for developing efficient irrigation strategies, particularly in water-deficient regions. The double-deck surface air layer (DSAL) model, a new aerodynamic method proposed by Kobayashi et al. (2013), is used for estimating the evaporation loss from a running water surface in irrigation canals. In this study, based on the long-term meteorological measurements made at automatic weather stations in 2013 and the field experiment conducted at - midstream areas of the Heihe River Basin (HRB), northwestern China, the DSAL model was applied to estimate the long-term evaporation loss from irrigation canals, which was the remarkable highlight of the study. The results showed that the rate of evaporation from irrigation canals exhibited a concave-up trend for the period from June to September, with higher values in June and September (20 to 50 mm day−1) and lower values in July and August (around 10 mm day−1). During the four months, for the Yingke and Daman irrigation districts in the Zhangye Oasis, the total water losses from irrigation canals due to evaporation were approximately 23.9 × 105 m3 and 36.6 × 105 m3, or 3.2% and 4.8% of the total amount of irrigation water, respectively. Results of the study are not only important for improving the irrigation water use efficiency, but also are beneficial to develop sustainable water resource management in the midstream areas of the HRB.

Some practical aspects of predicting texture data in digital soil mapping

Soil texture is the most well-known composition in soil science. When separate components of the texture (sand, silt, and clay) are predicted independently in digital soil mapping (DSM), there is no guarantee that the separate estimates will sum to 100%. Log-ratio transformations before DSM modelling are alternatives to guarantee a constant sum of the estimates. Little is known about the effect of non-summing to 100% and transformations of particle-size fractions (PSFs) when DSM products were used to predict soil functional properties using pedotransfer functions (PTFs). Therefore, this study was conducted to investigate the effect of different soil texture modelling methods on the estimation of available soil water capacity (AWC) and the total amount of irrigation water (TIW) required for wheat production on a 4600 ha area in Khuzestan province, southwestern Iran. Specifically, this study aimed i) to assess the performance of random forest models (RF) to predict untransformed (UT) and transformed PSFs using environmental covariates; ii) to study the effects of three widely used log-ratio transformations including additive, centroid and isometric log-ratio transformations (alr, clr, and ilr respectively) on the estimations of AWC and TIW. A total of 150 soil samples were collected from the surface layers (0–30 cm) based on the conditioned Latin hypercube sampling (cLHS) procedure. Results indicated that, in terms of root mean square error (RMSE), RF provided similar accuracies in predicting PSFs for both untransformed and transformed data. However, transformation resulted in biased estimates. In addition, RF prediction based on untransformed data resulted in more correctly soil texture classes allocation when compared to transformed data. The spatial distribution of the sum of the predicted untransformed fractions indicated only small parts of the area conformed to the 100% sum. Almost the same accuracies for estimates of AWC were obtained when both untransformed and transformed predicted texture components were used as the inputs to PTFs. Data transformation can result in biased estimates of AWC. The findings indicated no significant difference between transformation methods in predicting AWC and TIW. The general patterns of the spatial distribution of the predicted AWCs across the whole area were the same for transformed and untransformed data (except for clr transformation).

Modeling soil water balance and irrigation strategies in a flood-irrigated wheat-maize rotation system. A case in dry climate, China

Demand for irrigation water has been steadily increasing in arid regions where intensification of crop production is supported by flood-irrigation. An assessment of irrigation performance, water productivity, and irrigation schedules is critical to water conservation in dry climates. In this study, we conducted a field experiment to compare soil water balance in a flood-irrigated wheat-maize rotation system during the growing season of 2015–2016. We then modeled the soil water balance and improved irrigation strategies by coupling Hydrus-1D with the CROPWAT model, and using evapotranspiration calculated from climatic data. The calibrated Hydrus-1D model was used to simulate the temporal and spatial variation of evapotranspiration and deep percolation based on measured soil water distribution of soil profiles in the unsaturated zone. Results showed that using soil hydraulic parameters from inversion modeling can simulate soil water flow in multi-layer soil during a crop growing season. Simulation results indicated that about 36.6 and 40.6% (478.6 and 680.1 mm) of total water input in 2015 and 2016, respectively, was consumed by evapotranspiration. Furthermore, simulated deep percolation amounted for approximately 32.3 and 42.9% (403.9 and 696.6 mm) of the total amount of irrigation water in 2015 and 2016, respectively. These results indicated that only a small proportion of irrigation water was used by crops for transpiration. In addition, irrigation performance indicators such as relative water supply, relative irrigation supply, depleted fraction, and overall consumed ratio values indicated poor performance of irrigation practices in the study area. Particularly, crop yields did not increase with increases in irrigation water in flood-irrigated fields during the last ten years. Results of the CROPWAT model indicated that combinations of a fixed irrigation depth and timing, of 40 mm every 10 days, and 50 mm every 10 days were reasonable for wheat and maize, respectively, given the sandy soil in the study area. The improved irrigation strategies will limit water irrigation loss to 20% without significant effects on crop yields. This study provides an alternative approach for estimating deep percolation and crop water requirements supporting management efforts in water conservation in dry climates.

Rainwater Harvesting in Greenhouses Establishments and Use as Irrigation Water

Rainwater collection systems are an alternative water supply method that provides environmental and economic benefits according to traditional water supply methods in arid and semi-arid climates. Rainwater harvested in greenhouse roof by rain gutters can be used to irrigate and grow the plants cultivated in greenhouses. However, rain gutters and storage tanks in greenhouses should be of sufficient size to collect rainwater. Water consumption of plants in the greenhouse should be calculated correctly to determine the storage size in greenhouses. In this study, daily water consumption of tomatoes cultivated in greenhouses not regularly heated in Kumluca district of Antalya province is calculated according to FAO Penman Monteith method. Then, the storage capacity of the remaining part of the falling monthly rainfall used in the greenhouse was determined. As a result of the study, the amount of annual irrigation water harvested from rainfall in Kumluca district where total rainfall is 734.44 l/m2 was determined as 661.00 l/m2 based on rainfall factor of 0.9. In the period between September and June when single crop was grown in the year, the total amount of irrigation water needed by the plants in the not regularly heated greenhouse was calculated as 569.86 l/m2. Accordingly, it was determined that it is possible to meet all of the irrigation water to be provided to the plant with rainwater harvesting. Depending on the amount of rainwater harvest obtained, it was determined that the storage capacity of 0.40 m3/m2 in greenhouse is needed. In the study, it was determined that rainwater harvesting may contribute to the development of agricultural activities in areas suffering from water scarcity. Keywords : Greenhouse, Rainwater harvest, crop water requirement, Collection systems. DOI : 10.7176/JSTR/5-5-01

RAINWATER HARVESTING ON GREENHOUSE ROOF AND USE IN IRRIGATION

Rainwater collection systems are alternative water supply methods providing environmental and economic benefits compared to traditional water supply methods used in arid and semi-arid climates with water shortages. Rainwater harvested in greenhouse roof by rain gutters can be used to irrigate and grow the plants cultivated in greenhouses. However, rain gutters and storage tanks in greenhouses should be of sufficient size to collect rainwater. Water consumption of plants in the greenhouse should be calculated correctly to determine the storage size in greenhouses. The amount of annual irrigation water harvested from rainfall in Kirsehir province where total rainfall is 388.3 l/m2 was determined as 349.57 l/m2 based on rainfall factor of 0.9. Total amount of irrigation water needed by the plants in the unheated greenhouse between April and September for single crop cultivation was 568.33 l/m2. The results revealed that 61.49% of irrigation water needed for plants can be met by rainwater harvesting. In addition, 47.74% of the total water demand of plants in the heated greenhouse where crops are grown throughout a year can be met by rainwater harvesting. The storage capacities needed for unheated and heated greenhouses were determined as 0.21 m3/m2 and 0.30 m3/m2 depending on the amount of rainwater harvested. The results showed that rainwater harvesting may contribute to the improvement of agricultural activities in water-scarce regions.

Water balance in direct-seeded rice under conservation agriculture in North-western Indo-Gangetic Plains of India

Direct-seeded rice (Oryza sativa L.) (DSR) supported by conservation agriculture (CA)-based crop management practices is perceived to address the challenge of producing more rice grain with less water. DSR is endowed with multiple benefits/advantages over transplanted puddled rice (TPR) through savings in labour (40–45%), water (30–40%), fuel/energy (60–70%), and reductions in greenhouse gas emissions. It can be an economic alternative to TPR, but the performance of CA-based no-till and residue retained DSR has been hardly studied. Therefore, this field experiment consisting of eight treatments was designed in the sixth year of a continuing experiment under CA-based rice–mustard cropping system to estimate and analyse water budgeting in rice. Results revealed that, in the 0–15 cm soil layer, both DSR and TPR plots showed similar soil moisture content (SMC) values at initial, developmental, mid-season, and late-season periods. However, the overall SMC in a triple zero-till system that constituted mungbean residue (MBR) + zero-till DSR (ZT DSR) − rice residue (RR) + zero-till mustard (ZTM) − mustard residue (MR) + summer mungbean (SMB) treatment was 9.7 and 10% in soil surface, and in 15–30 cm soil layer, 32 and 12.6% higher than that in TPR − ZTM and TPR − CTM (conventional till mustard) treatments, respectively. Irrigation water requirment, including effective rainfall, was the highest during the mid-season (380.2 mm), followed by the initial stage (312.9 mm). The total amount of irrigation water applied to DSR plots was 924.3 mm against 1441.4 mm in TPR plots, indicating a 517 mm water saving. The amount of water used for puddling and ponding in TPR was 135 and 96 mm, respectively. The best treatment (MBR + ZTDSR − RR + ZTM-MR + SMB) showed a deep percolation of 5.8 mm day−1 that was 26% lower than the highest deep percolation (7.8 mm day−1) observed in TPR–CTM. Thus, a DSR crop under the triple zero-till system with retention of crop residues for three seasons can be recommended for attaining higher crop and water productivity. An extrapolation of these results revealed that, by adoption of this technology, 60060 Mm3 of water can be saved which can irrigate 6.72 Mha additional rice areas in the entire IGP (Indo-Gangetic Plains; total area under rice–wheat cropping system is 10.5 Mha). This may also lead to the mitigation of climate change effects. This practice can be adopted in the irrigated rice-growing belts of the North-western IGP of India and in similar agro-ecologies of the tropics and sub-tropics.