Conservation of Water: Irrigation with recycled water in greenhouses

Author: Kobi Shilo, Chief Agronomist, NaanDanJain

As part of its efforts to take care of the environment through effective and efficient water management, NaanDanJain promotes irrigation with reclaimed water wherever possible. In today's high-tech era, more and more growers are embracing greenhouse crops. Roses are one of the leading greenhouse crops in Israel, grown hydroponically on volcanic rock or rockwool. NaanDanJain has installed systems that exploit recycled water for irrigation of greenhouse crops as well as nearby fields, orchards and plantations.

One of the recycling projects designed, supplied and installed by NaanDanJain is at Moshav Renen, in southern Israel. Runoff water from its greenhouses is reclaimed to irrigate the greenhouse roses, saving precious water and liquid fertilizers. The system also prevents puddles, weeds and other problems created by surplus water that has been left to waste. The growers of Moshav Renen, have saved a lot of money by recycling both water and fertilizers that were not absorbed by the plants in the first irrigation.

Under the hydroponic system, water and nutrients are absorbed directly by the roots during irrigation. Surplus water and fertilizer do not accumulate in the soilless substrate, creating a runoff of up to 40%. The crops are irrigated up to 5 to 6 times a day, reaching 1.2 m3/ha, thereby creating a surplus of about 0.4 m3/ha.

NaanDanJain recommends construction of a small tank at the end of the greenhouse, wherever possible. Runoff is collected in this tank, and a pump returns water and nutrients to the greenhouse, or pushes them out into drip laterals which irrigate vineyards, plantations or any other nearby crop.

The water that is pumped from the tank is continuously tested by sensors to examine the water's salinity and pH. The recycled water quality is relayed to a special computer that reads the test results and dilutes the run-off with fresh water accordingly.

An additional water conservation system has been designed on Moshav Renen to collect rainwater in the winter. Special pipes installed on the greenhouse roofs direct rainwater to a 300 m3 tank. The rainwater is used to irrigate the greenhouse roses, as well as other nearby outdoor crops. This is excellent quality water, and is used for irrigation as well as for leaching of salt accumulated in the soil during the irrigation season.

NaanDanJain is aware that conservation (reduce, reuse, recycle) is an essential element in any water policy. We are committed to effective water and fertilizer management through a variety of innovative techniques, including conservation, water reclamation and reuse.


Article tags: efficient irrigation, greenhouses, recycled water