ECONOMIC-ANALYSIS OF INTEGRATED CROP MANAGEMENT-PRACTICES OF NAVEL ORANGES

The effect of various integrated crop management practices on producti vity (fruit yield, grade, and size) and returns of 'Washington Navel' oranges [Citrus sinensis (L.) Osbeck] was determined in the San Joaqui n Valley of California. Seventy-two combinations of treatments compris ed of three irrigation levels [80%, 100%, and 120% evapotranspiration demand (ETc)], three N fertilizer levels (low, medium, and high based on 2.3%, 2.5%, and 2.7% leaf N, respectively), gibberellic acid (+/-), miticide (+/-), and fungicide-nematicide (+/-) were included in the a nalysis. Using a partial budgeting procedure, returns after costs were calculated for each treatment combination. Costs of treatments, harve sting, packing, and processing were subtracted from the value of the c rop. The value of the crop was calculated as the sum of returns of cro p in each size and grade category. The overall result indicated that r eturns after costs were higher for the +fungicide-nematicide treatment and also were generally more with increased irrigation. The combinati on of 120% ETc, +fungicide-nematicide, medium or high N, -miticide, an d -gibberellin showed the highest return of all treatment combinations . Second highest returns mere obtained with high N or with miticide an d gibberellin used together.