A review on partial root-zone drying irrigation.

Abstract Available fresh water resources are subjected to an ever-increasing pressure due to extensive agricultural water demand for irrigated lands. A long-term perspective in shortage of fresh water resources, especially in arid and semi-arid area, highlights an urgent solution for innovative irrigation strategy and agricultural water management. This paper is a review on the wide applications of the partial root-zone drying irrigation (PRD) on diverse plant species. The PRD irrigation is a novel improvement of deficit irrigation in which half of the root zone is irrigated alternatively in scheduled irrigation events. In the last decade, scientists across the world, especially from arid to semi-arid countries, have extensively evaluated this irrigation as a water-saving irrigation strategy on agronomic and horticultural plants. This review paper focuses on the physiological and morphological aspects of PRD on plants and its ultimate impact on yield and water productivity. Overall, under limited water resources where water is precious, PRD is a viable irrigation option to increase water productivity while marinating the yield, rather than only increasing the economic yield without concerning the value of water in limited water environments

Supplemental irrigation management of rainfed grapevines under drought conditions using the CropSyst model

Aim of study: To determine how much water should be used and when it should be applied in rain-fed grapevine using a cropping system simulation model (CropSyst), and also the economic analysis of supplemental irrigation for rainfed grapevine.Area of study: This study was conducted at the School of Agriculture, Shiraz University, Shiraz, Iran, in 2012, 2013 and 2014.Material and methods: The CropSyst model was calibrated to predict the rainfed yields of ‘Askari’ and ‘Yaghooti’ grapevines in different climates using four amounts of SI: 250 L (I1), 500 L (I2), 1000 L (I3) and 0 (I4), five SI times: single in March (T1), single in April (T2), single in March + single in April (T3), single in May (T4) and single in June (T5).Main results: Treatment T3 increased the average simulated yield of ‘Askari’ by 15% to 40% at regions with P/ETo>0.6, 17% to 61% at 0.2<P/ETO<0.6, and 26% to 61% at P/ETO<0.2, while in ‘Yaghooti’ it increased about 2% to 41% at regions with P/ETo>0.6, 4% to 36% at 0.2<P/ETO<0.6 and 2% to 26% at P/ETO<0.2. By increasing the water price by 30% and 50%, net benefits for the ‘Askari’ decreased by about 31% and 54%, while 6% and 18%, for ‘Yaghooti’ respectively.Research highlights: The CropSyst model can successfully predict soil water content and grapevine yields. Application of SI in May increased significantly the grapevine yield as compared to other SI times

Estimating the furrow infiltration characteristic from a single advance point

Management and control of surface irrigation, in particular furrow irrigation, is limited by spatio-temporal soil infiltration variability as well as the high cost and time associated with collecting intensive field data for estimation of the infiltration characteristics. Recent work has proposed scaling the commonly used infiltration function by using a model infiltration curve and a single advance point for every other furrow in an irrigation event. Scaling factors were calculated for a series of furrows at two sites and at four points down the length of the field (0.25 L, 0.5 L, 0.75 L and L). Differences in the value of the scaling factor with distance were found to be a function of the shape of the advance curves. It is concluded that use of points early in the advance results in a substantial loss of accuracy and should be avoided. The scaling factor was also strongly correlated with the furrow-wetted perimeter suggesting that the scaling is an appropriate way of both predicting and accommodating the effect of the hydraulic variability

Interaction of different irrigation strategies and soil textures on the nitrogen uptake of field grown potatoes.

Abstract Nitrogen (N) uptake (kg ha -1 ) of field-grown potatoes was measured in 4.32 m 2 lysimeters that were filled with coarse sand, loamy sand, and sandy loam and subjected to full (FI), deficit (DI), and partial root-zone drying (PRD) irrigation strategies. PRD and DI as water-saving irrigation treatments received 65% of FI after tuber bulking and lasted for six weeks until final harvest. Results showed that the irrigation treatments were not significantly different in terms of N uptake in the tubers, shoot, and whole crop. However, there was a statistical difference between the soil textures where plants in the loamy sand had the highest amount of N uptake. The interaction between irrigation treatments and soil textures was significant, and implied that under non-limiting water conditions, loamy sand is the suitable soil for potato production because plants can take up sufficient amounts of N and it could potentially lead to higher yield. However, under limited water conditions and applying water-saving irrigation strategies, sandy loam and coarse sand are better growth media because N is more available for the potatoes. The simple yield prediction model was developed that could explains ca. 96% of the variations of fresh tuber yield based on the plant evapotranspiration (ET) and N uptake in the tuber or whole crop

The effect of physical and chemical treatments on runoff, infiltration and soil loss

ARTICLE INFO ABSTRACT-In recent years, intensive drought has caused a severe yield reduction in rain-fed trees. Increasing runoff of low amount rainfall can be used to provide partial water requirement of rain-fed trees. To achieve this objective, some strategies including gravel removal (G), rill construction across to slope (R) and applying of baking soda (S) and their effects on runoff, rainfall infiltration and soil loss were simulated by a laboratory rainfall simulator under 33 mm h -1 intensity in 60 minutes. The results showed that the combination of R + , G -and S + significantly increase the soil loss, runoff, and runoff coefficient 14.43, 2.74 and 1.59 and decrease rainfall threshold and infiltration 2.1 and 1.57 times compared to the control, respectively. Separately, S + , R + and G -were the most effective in the runoff enhancement (31.2, 29.3 and 22%) and in infiltration reduction (8.4, 7 and 5%), respectively. S + had the most effect on soil loss due to dispersion of soil surface. Furthermore, the effect of R + was more visible than G -in increasing the soil loss. Applying sodium bicarbonate (S) increased the sodium in runoff and sediment, but there were no salinity (EC= 0.51-0.60 dS m -1 ) and sodicity (SAR= 0.34-0.73) hazard in runoff. In saturated extract of sediment, the salinity (EC= 1.75-2.23 dS m -1 ) and sodium (SAR= 1.96-3.45) hazard were relatively high and low, respectively. Although, chemical treatments (S) did not show the sodicity hazard very much, the use of S must be considered carefully