2013 ASHS Annual Conference

Lettuce growers on the central coast of California are under increased regulatory pressure to reduce nitrate loading to ground and surface water supplies.  Two tools available to farmers to improve nitrogen use efficiency of lettuce are the soil nitrate quick test (SNQT) for monitoring soil mineral nitrogen levels and weather-based irrigation scheduling for estimating water needs of the crop.  We developed a web-based software application, called CropManage (https://ucanr.edu/cropmanage), to facilitate the implementation of both of these tools. Users can access the software through a web browser on their smart phones, tablet, and desktop computers. The software allows growers to quickly determine an optimal fertilizer N rate based on the SNQT and N uptake curves for lettuce.  In addition, the software estimates the water requirement of the crop using evapotranspiration data from the California Irrigation Management Information System and models of canopy development. Preliminary field testing of the software in commercial fields demonstrated that growers can significantly reduce N fertilizer and water use without reducing quality and yield of lettuce.  A demonstration trial comparing the CropManage fertilizer N recommendation with the grower standard practice resulted in similar commercial yields using almost 30% less N fertilizer. The other trial comparing the irrigation recommendation of CropManage with the grower standard practice resulted in a 25% savings in water following the CropManage irrigation schedule during the drip phase of the crop, and equal commercial yields between treatments.