Legume break crops may contain significant amounts of nitrogen. Nitrogen fertiliser rates in the plant cane crop should be adjusted to account for available nitrogen from the legume crop.
- Legumes break the sugarcane monoculture between crop cycles.
- In general, legumes improve soil condition, add organic matter to the soil, protect soil from erosion during the wet season and help reduce pest, weed and disease pressures.
- Some legumes are affected by specific nematodes hosted by sugarcane. Legume crop selection should take this into account. An information sheet can be found here.
- Nodulation of the legume crop is susceptible to low soil pH, resulting in reduced nitrogen fixation. Consequently, fields selected for legume break crops should have a soil pH (water) above 5.5 or be limed to reach a soil pH (water) above 5.5.
- Legume crops should be inoculated at planting with the appropriate group of Rhizobium bacteria to stimulate nodulation.
- Excessive nitrogen fertiliser should not be applied to a legume crop as this will inhibit nodulation and the ability/necessity for the crop to fix atmospheric nitrogen.
- Well-grown legume crops can contribute significant amounts of nitrogen to the soil. The amount available to the plant cane crop will depend on legume biomass and nitrogen content, legume termination method, tillage and rainfall.
- Non-legume and mixed species cover crops are also grown in sugarcane farming systems. Further work is required on these systems to understand how they affect nutrient availability.