Variable rate application technology for optimizing alfalfa production in arid climate.

Khalid A.  Al-Gaadi; Virupakshagouda C.  Patil; Elkamil H. M.  Tola; Rangaswamy  Madugundu; Samy A.  Marey; A. M.  Al-Omran; Ali  Al-Dosari

Khalid A. Al-Gaadi Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia;Precision Agriculture Research Chair, King Saud University, Saudi Arabia

Virupakshagouda C. Patil Precision Agriculture Research Chair, King Saud University, Saudi Arabia

Elkamil H. M. Tola Precision Agriculture Research Chair, King Saud University, Saudi Arabia

Rangaswamy Madugundu Precision Agriculture Research Chair, King Saud University, Saudi Arabia

Samy A. Marey Precision Agriculture Research Chair, King Saud University, Saudi Arabia

A. M. Al-Omran Department of Soil Science, College of Food and Agriculture Sciences, King Saud University, Saudi Arabia

Ali Al-Dosari Department of Geography, College of Arts, King Saud University, Saudi Arabia

This study was to investigate the benefits of variable rate application technology for optimum production of alfalfa in arid climate. The study area was divided into two management zones by employing Fuzzy c-means cluster analysis. A field experiment was conducted in Split plot design. Irrigation treatments allocated to the main plots in January 2012 included: Irrigation at evapotranspiration (ETc) of 100% (I1 ≈ 3130. 54 mm/ha/annum), 90% (I2 ≈ 2817. 49 mm/ha/annum), 80% (I3 ≈ 2504. 41 mm/ha/annum), and 70% (I4 ≈ 2191. 38 mm/ha/annum). The fertilizer levels (N:P2O5:K2O kg/ha/year) allocated to sub plots included: F1 – low (126:92:300), F2 – medium (234:138:400) and F3 – high (342:184:500). After retrofitting of variable rate irrigation (VRI) system on to the center pivot in May 2012, fertilizer levels formed main treatments and irrigation levels formed sub-treatments. The highest yield in both the harvests was obtained by irrigation at 80% ETc . Across the two management zones and two harvests made in September and October 2012, medium fertilizer level (@ 234:138:400 kg/ha/year of N: P2O5:K2O) resulted in higher alfalfa yield than the other two fertilizer levels. VRI showed benefits only in September 2012 harvest. In this harvest, adoption of VRI at 70% ETc in MZ1 and 80% ETc in MZ2 resulted in water saving of 30 and 20%, respectively. The following conclusions can be drawn from this study: 1. Variable rate application of irrigation water for the two management zones resulted in water saving of up to 30% in one out of two harvests. 2. Variable rate application of fertilizers was not effective and uniform rate application of fertilizers @ 234:138:400 kg/ha/year of N: P2O5:K2O resulted in higher alfalfa yield in both the management zones