Green but not much grass!
Dairy farmers in the lower North Island are working on protecting next season, according to Federated Farmers dairy chair Richard McIntyre, who farms just north of the Horowhenua township of Levin.
The key attributes of catch crops when following autumn or winter grazed crops are that they: are cold tolerant, winter active and have fibrous deep root systems capable of removing nitrogen at depth.
Catch crop benefits vary depending on weather conditions, particularly during establishment, with direct-drilling or light pre-drilling cultivation being recommended methods where possible to minimise nitrogen mineralisation.
The gross margins (revenue minus costs) and cents/kgDM of catch crops can be used to compare different crops.
The numbers will vary depending on the yield and how the crop fits into an individual farm system, which is influenced by catch crop sowing date, the timing of feed requirements and the sowing date of the following crop or pasture.
The Forages for Reduced Nitrate Leaching (FRNL) research trials gross margin and c/kg DM varied from $173/ha to $1263/ha and 8.1 c/kg DM to 15.3 c/kg DM respectively.
FRNL ran trials of different crops comparing crop nitrogen uptake and residual soil nitrogen as indicators of the risk of nitrate leaching.
A variety of species or combinations can be used as catch crops. Consider the below when selecting species or combinations thereof:
Establishment opportunities of the catch crop; what is the usual soil temperature at the time of planting and can heavy machinery normally access the paddock at that time of year?
Main crop/regrassing planting date; consider effect on potential yield of the following crop or pasture.
Ability to fit into the farm system, e.g. planned crop rotation, harvesting or grazing dates, end use of land planted (permanent pasture or crop), use of catch crop:
- green manure
- grazing
- green chop/whole crop silage
- grain or straw
Examples of Catch Crops
- Oats: A low temperature germinating, fast-growing cereal that can be sown in autumn, winter and spring. Used for winter green feed, green manure or silage.
- Triticale: Tall cereals developed from crossing wheat and ryecorn, some varieties can be planted in autumn and winter behind grazed crops.
- Ryecorn: Used in dryland situations where it is sown in early summer for grazing through until spring.
- Italian ryegrass: Establishes quickly and will grow at lower temperatures than perennial ryegrass. It can be sown by itself or in combination with a cereal crop.
- Faba beans: Best planted between early March to late April following a summer crop to use as a late spring feed. This legume fixes nitrogen, which in some crop rotations can be beneficial for the next crop.
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