Winter, spring, and summer harvest management effects on the cut yield of dry matter and protein in irrigated Wairau lucerne

Abstract

A single season trial was carried out at Lincoln University, Canterbury, New Zealand, on a Wakanui silt loam, with cv "Wairau" lucerne under irrigation. Three management practices were examined in their various combinations: Grazing in winter (early July), stage at which first harvested in spring (cut when 30 cm tall, 50 cm tall and 60 cm tall), and stage at which harvested in summer (cut at 1% bloom, cut at 50% bloom). Dry herbage yield and crude protein yield were measured.

Results showed that: 1. Winter grazing depressed yield by 7% except where spring cutting was left until the plants were 60 cm tall. 2. Spring cutting height optimum was 50 cm when ungrazed in winter and 60 cm when grazed in winter. 3. Cutting in summer when plants reached 50% bloom gave a 3% yield advantage over cutting when they reached 1% bloom at the 50 cm spring treatment. 4. Treatment means for total season's herbage yield ranged from 20000 kg ha⁻¹ DM to 23 460 kg ha⁻¹ DM. 5. Crude protein yield was not affected by any of the treatments except grazing in winter which gave 6.9% less yield than not grazing in winter. The highest yielding treatment combination produced a total season's yield of 5290 kg ha⁻¹ of crude protein.