Effect of nitrogen fertiliser supply and winter cutting on morphological composition and herbage digestibility of aDactylis glomerata L sward in spring
✍ Scribed by Duru, Michel; Delprat, Vincent; Fabre, Catherine; Feuillerac, Estelle
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 168 KB
- Volume
- 80
- Category
- Article
- ISSN
- 0022-5142
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✦ Synopsis
The aim of this study was to improve the prediction of sward digestibility in spring as affected by nitrogen supply and winter cutting, taking into account their effects on the leaf:stem ratio and the digestibility of the plant parts. Two nitrogen treatments (120 kg ha À1 and nil) and two cutting regimes were studied over three growing seasons. Herbage digestibility measurements were made about 2 weeks before and after the heading stage. Nitrogen de®ciency always decreased the proportion of stem in the herbage yield signi®cantly, mainly because it reduced or delayed the number of tillers which reach the double-ridge stage. The stem digestibility was higher when no nitrogen was supplied. We show that it decreased with increasing stem length, whatever the sampling date and the growing season. Morever, for a given stem length we noticed a positive effect of herbage nitrogen status, probably because the stem weight per unit length was lower when N was supplied. Green lamina digestibility decreased more slowly than that of stem, but at a different rate according to the growing season. At the whole herbage level, nitrogen supply always decreased the herbage digestibility, and sometimes cutting in winter increased it. These trends resulted mainly from the effect of nitrogen supply on the proportion of stem in the herbage and its digestibility.