Influence of irrigation on dry matter production, leaf composition, and nutrient removal by turnip

Abstract

Irrigation scheduling of leafy greens generally consists of applying 19 mm of water every four days, which leads to irrigation depths that exceed the soil water deficit, and requires fertilizer applications higher than recommended rates. We determined the influence of irrigation scheduled by class A pan evaporation and a variable crop factor on leaf tissue composition and nutrient removal by turnips using a continuous moisture gradient and different N fertilizer conditions. Irrigation maintained foliar concentrations of N, P, K, Ca, and Mg in the sufficiency range. During dry periods, increasing irrigation increased P, decreased Mg, and had little effect on N, Ca, or K foliar concentrations. Micro‐nutrient concentrations in the leaves responded to irrigation rates, but within a narrow range. Excessive water applications, due to rainfall or to irrigation rates higher than the model rate, consistently reduced nutrient crop removal. Since a combination of water applications that did not exceed soil water deficit and current fertilizer applications maintained adequate nutrient status and maximized nutrient crop removal, apparent need for N fertilization in excess of the recommended rate for turnips is due to excessive water applications.

Notes

Corresponding author

Professors of Horticulture.