Time of harvest

As lucerne maturity increases, yield increases but quality decreases. This is because the proportion of fibrous stems increases and the percentage of leaves decreases. Lucerne leaves are high in protein and low in fibre so the highest quality lucerne silage is cut in the pre-bud to bud stage when the leaf-to-stem ratio is highest.

Table 5: Feed analysis of lucerne cut at various stages of maturity12
 Percentage drymatter basis     
Stage




Leaves % of total DM yield  Crude Protein (%)  Acid detergent fibre (ADF, %)  Neutral detergent fibre (NDF, %)  Metabolisable energy (MJME per kg/DM)
Bud > 40 > 19 > 30 < 40 11.5
Early bloom  30 - 40 16 - 19 30 - 35  40 - 45 11.0
Mid bloom    20 - 29 13 - 15 36 - 40 46 - 50  10.5 
Full bloom < 30 < 13  > 40 > 50 10.0

The first cut should be taken early in the season when the plants are around 30 cm in height. Leave a 10 cm residual after cutting to avoid damaging the crown buds and to promote tillering of the plant. Second and subsequent cuts should be taken at 28 - 33 days later or at mid bud (whichever is earliest).

Autumn harvest management of lucerne in cool regions (lower South Island and at altitude) involves balancing the need for extra feed against the risk of crop damage due to winter injury. When the previous cutting interval has been 35 days or less, avoid harvesting before the first winter frost. This allows plants to enter the winter with higher carbohydrate root reserves. Leaving stem and leaf stubble insulates the crown of the plant and reduces the risk to the crop.

 

12Pioneer Lucerne Manual. 2015. Genetic Technologies Limited, Auckland NZ.