2014 AWD Trial Summary

Last summer we discussed the potential benefits of properly managing and irrigating multiple inlet rice fields. The advantages of multiple inlet include rapid flood establishment, reduced N loss, and more precise and easier flood control.  The greatest advantage of multiple inlet irrigation is it facilitates the adoption of other irrigation practices. AWD or alternate wetting and drying, is one such irrigation practice.

AWD is a water-saving technology that farmers can use to reduce the amount of irrigation water used in rice fields without any yield penalty. In AWD, farmers allow the flood water to recede to a “muddy” state before re-flooding the field. The number of days of non-flooded soil between irrigations can vary from 1 day to more than 5 days depending on soil type, weather and crop growth stage. This process lowers the total time pumping in addition to capturing rainfall.

During 2014 we had three farmer “on farm” AWD irrigation trials. Each farmer agreed to irrigate his field conventionally through levee gates, via multiple inlet, and an additional multiple inlet field utilizing AWD. The farmer originated irrigation on the conventional and multiple inlet fields, while the MSU researcher scheduled irrigation on the multiple inlet, AWD field. The MSU researcher allowed the field to drain to a muddy state while analyzing the rainfall potential before making the decision to irrigate. The multiple inlet field held “at capacity” permitted the rainfall to become runoff.

Farmer 1 is very familiar with multiple inlet and AWD flood management and presently manages his water aggressively resulting in only marginal differences between treatments. Farmer 2 is new to multiple inlet and presently manages the multiple inlet field much like a conventional field. Farmer 3 utilizes each well to irrigate multiple fields and maintains his rice fields “at capacity” much of the time. Farmer 3 has been utilizing multiple inlet for many years and is very familiar with the system. Because Farmer 3 tends to keep his field at capacity, only limited amounts of rainfall can be captured.

Results from the 2014 trails are summarized below. Included are the yield and water use data for each grower location as well as an average of all data.  The fields irrigated with conventional levee gates had an average water use of 28.33 acre inches.  The use of multiple inlet reduced water use by 2.66 acre inches with an average of 25.67 acre inches used. Through the use of AWD, we were able to further reduce water use by an average of 11 acre inches. This resulted in an average water savings of $33 per acre over the conventional irrigated field. Our on-farm data indicate that multiple-inlet, AWD maintains yield potential of conventionally irrigated systems while significantly reducing water use.

  The photos at the top of the article are 100% headed photos from the AWD treatment fields.