Tomato Yield and Nitrogen Recovery as Influenced by Irrigation Method, Nitrogen Source, and Mulch

Abstract

Factorial combinations of trickle or overhead irrigation, polyethylene mulch or no mulch, and 100% NH 4 NO 3 or 50% sulfur-coated urea (SCU) and 50% NH 4 NO 3 were evaluated for their effects on yield and N recovery by tomatoes ( Lycopersicon esculentum Mill). In treatments using 100% NH 4 NO 3 , 15 N-depleted NH 4 NO 3 was applied. Neither tomato yield nor N uptake were affected by irrigation method but both were increased by the use of polyethylene mulch. Higher yields were obtained with NH 4 NO 3 than with 50% NH 4 NO 3 and 50% SCU. An average of 65% of the N in the plant and fruit originated from fertilizer N. Nitrogen recovery from plants and soil at the end of the season in treatments using 15 N-depleted fertilizer ranged from 52% to 95%. Highest recovery was obtained with mulch plus overhead irrigation. With this system, 53% of the added N was recovered by the plant and 42% remained in the soil. Only 5% of the added N was lost from the system. All of the other treatments resulted in loss of an average of 46% of the added N.