Microirrigation continues to grow in various parts of the country as more information about installation, operation, maintenance and irrigation management is developed by scientists cooperating on this project. Expansion of drip-irrigated corn, onion, almonds grapes and apples is related to research efforts.

Micro irrigation has the potential to reduce water use, leaving more water in streams, reservoirs, or groundwater. Surface water contamination of streams can be less with micro irrigation than with surface flood irrigation and groundwater contamination by nitrate and pesticides can be sharply lower. The environmental benefits of micro irrigation can only be achieved if micro irrigation proves to be economically feasible through reductions in other costs not related to the added costs of the micro irrigation system and improvements in crop yield or quality.

The field days and grower demonstrations offered participants the opportunity to observe microirrigation in a field settings across the nation. Growers were able to gain 'hands-on' experience with drip irrigation systems and new design features. Testing and demonstration of variable irrigation criteria and variations in drip system designs provided growers scientific results to optimize their yields of vegetable, fruit, seed and cereal crops while minimizing input costs.

Plant-based RDI has allowed 40 to 50 percent reductions in irrigation water applied to prune trees, while maintaining or improving economic yields. Water savings in almonds have depended on soil type and depth, with the most substantial water savings on the deepest soils.

Work on grape irrigation for juice has encouraged more grape growers to install drip irrigation systems, especially for newly planted Niagara grapes, a growth component of the industry. This work led to the NY industry research award, attesting to its impact on the grape and wine industry. Also there has been a significant increase in grower interest in and installations of irrigation systems for apples and wine grapes in the Northeast.

Drip-irrigated onion has demonstrated increases in onion yield and grade on sites that are difficult to irrigate using other systems. The expansion of drip-irrigated onion has been linked to vastly reduced N inputs and no irrigation-induced erosion and associated pollutant runoff. Thirty to 40 percent less water was required using SDI than with surface irrigation systems.

Production function, crop coefficient, and the water use efficiency of corn was established for arid environments under SDI. The result can be used as benchmark for irrigation design and management in growing corn in arid areas of the world.

The salinity study reveled that corn under subsurface drip irrigation can tolerate higher salinity levels than what is reported in the literature. This is a significant finding in that it will help farmers save water by using poor quality water and lower leaching fraction and achieve a good yield level. Determining the threshold salinity value for corn and the yield reduction per unit of salinity under subsurface drip irrigation will help farmers also develop best management practices necessary when using poor quality water for SDI.

Subsurface drip irrigation has the potential for improving water use efficiency, reducing weed growth, and improving overall energy efficiency. The GPS guidance system allowed for automatic steering of the tractor and implements close to the buried drip-tape and plants without causing damage to either while operating at relatively high operational ground speeds.

Various drip tape materials may plug. Others may distort and deliver varying amounts of water following stress from tension or temperature Determining the performance of tape allowed growers to purchase more reliable products and provided manufacturers with unbiased feed back to improve their commercial products.

Cooperative work between several states is testing poplar tree clones for productivity using drip irrigation under the constraint of high pH soils. New commercial poplar plantings are being established as a result of this work.