Nitrogen Availability for Sugarbeet affected by Tillage System and Sprinkler Irrigation Method

Abstract

Many shank‐type strip tillage (ST) implements band fertilizer below the seed without incorporating crop residue into the soil, potentially affecting N availability. Sprinkler irrigation method may also affect N availability due to its influence on water and NO3–N movement in soil. A field study was conducted at Sidney, MT, to determine if sugarbeet (Beta vulgaris L.) petiole NO3–N concentration and soil available (i.e., mineral) N distribution differ under (i) conventional tillage (CT) and ST systems and (ii) mid‐elevation spray application (MESA) and low energy precision application (LEPA) irrigation methods. Mid‐season petiole NO3–N concentration was lower with ST than with CT in 1 of 3 yr. In‐season mineral N concentration in the top 45 cm of soil was lower with ST than with CT. Postharvest mineral N was 10% lower with ST than with CT. There were few measurable effects of irrigation method except that in‐season mineral N in the top 45 cm of soil was 10% greater with LEPA than with MESA. Root yield and sugar production were reported to be similar with the two tillage systems. It was concluded that differences in petiole NO3–N concentration and soil mineral N content were not sufficient to justify altering N application rate based on the tillage systems or irrigation methods evaluated. However, there were indications that NO3–N leaching may be reduced by combining LEPA, with which irrigation water is applied between alternating crop rows, with strip tillage, where N is banded beneath the crop row.