The effects of irrigation and nitrogen fertilization on the ensiling of safflower ( Carthamus tinctorius)

Abstract

Safflower plants were grown in central Israel (500 mm annual rainfall) under different additional irrigation (ranging from 39.1 to 182.6 mm) and nitrogen fertilization (0 and 300 kg ha −1) regimes. Plants grown under the various irrigation-fertilization combinations were harvested at the budding and full-bloom stages and ensiled in 1.5–l anaerobic glass jars. Three jars from each combined treatment were sampled at predetermined dates for pH measurement and LAB (lactic acid bacteria) enumeration. After 35 days the silages were fully analyzed and subjected to an aerobic stability test. Results indicated that irrigation affected DM content but did not consistently affect DM yield, water-soluble carbohydrate content or the preservation quality of the safflower silages. Nitrogen fertilization increased the buffering capacity of the safflower plants (23 mequiv. versus 18 mequiv. per 100 g DM with and without nitrogen fertilization, respectively), but improved the ensiling of safflower, as shown by smaller fermentation losses, higher lactic acid production and improved aerobic stability. Our result suggest that decisions relative to N fertilization in safflower for silage should take into account not only the N concentration of the freshly cut forage, but also the implications on the ensiling process.