|PHENE, CLAUDE - Consultant|
|PHENE, REBECCA - University Of California|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/20/2015
Publication Date: 6/2/2015
Citation: Ayars, J.E., Phene, C.J., Phene, R.C. 2015. Water and nitrogen requirements of subsurface drip irrigated pomegranate. Meeting Proceedings. p. 149-158.
Interpretive Summary: As the competition for water increases between agriculture, the environment, and municipal supplies, it will be incumbent on irrigated agriculture to improve water management. Subsurface drip irrigation has been demonstrated to be very effective in improving irrigation efficiency through reductions in evaporation and deep percolation losses. Fertilization through drip irrigation has also been shown to be very effective in improving fertilizer use efficiency through better plant uptake and reduced losses from deep percolation. We have combined these technologies to determine the water and nutrient requirements for a developing pomegranate orchard. Even though pomegranate is an ancient crop, very little is known about its water requirements and nutrient requirements. Pomegranate juice is prized for it's nutritional qualities and there has been an increase in the acreage in California to meet this demand. Pomegranate is considered a drought and salinity tolerant crop as well and thus is well suited for production in California. We used a replicated trial to determine the water requirement and nitrogen requirement. A mature plant will use approximately 31 inches of water when grown with subsurface drip irrigation compared to 33 inches using surface drip. The fertilizer use efficiency was greater in subsurface drip irrigated than in surface drip irrigated plots. The marketable yields were approximately 15 t/ac in 2014. Since this was a developing orchard the yields increased each year and 2014 will be representative of a mature orchard. The subsurface drip irrigated plots had greater yields than the surface drip plots each year. The combination of lower amounts of applied water and greater yields in the subsurface drip plots resulted in greater water use efficiency for the subsurface irrigation compared to the surface drip irrigated plots. This is consistent with the results in many other crops that are irrigated with subsurface drip.
Technical Abstract: Surface drip irrigation is a well-developed practice for both annual and perennial crops. The use of subsurface drip is a well-established practice in many annual row crops, e.g. tomatoes, strawberries, lettuce. However, the use of subsurface drip on perennial crops has been slow to develop. With the on-going drought, interest has increased for use on both annual and perennial crops because of the ability to improve water productivity and reduce applied water. Pomegranate acreage in California is approximately 25,000 acres. However, there is very little information about the water and nutrient requirements of the crop. We developed a replicated trial to determine the water and nutrient requirements of a maturing pomegranate crop being grown with surface and subsurface drip irrigation. The system is controlled by a weighing lysimeter that irrigates both systems when 1 mm of crop water use has been measured. Nitrogen fertilizer is injected with the irrigation water at 50%, 100%, and 150% of what is considered adequate for the N needs of the crop. The marketable yields were 15.7 and 14.8 t/ac for the SDI and DI respectively in 2013 and 21.2 and 18.1 t/ac in for the SDI and DI in 2014. The water use efficiency was higher in the SDI plots compared to the DI plots in both years. The applied water in 2014 was 31 inches in the SDI treatments and 33 inches in the DI treatments. Applied nitrogen ranged from 55 to 305 lbs/ac over 2013 and 2014.