Grass breaks can raise soil fertility
WINTER wheat or barley grown with half-rate inputs between two-year grass breaks can produce rotational gross margins as good as or better than cereals-only cropping with full-rate inputs.
The trial in Northern Ireland compared a six-year arable rotation with a four-year arable rotation followed by two years of grass.
The two-year grass break raised the fertility of the soil for arable crops in the following two, and possibly three seasons, said Lindsay Easson. An extra 30-50kg/ha of nitrogen was mineralised in the soil in the two years after a grass break. Weed and disease pressure also appeared to be less.
Yields and gross margins were consistently higher in the mixed rotation at all input levels. Halving fertiliser use had more impact on yield (down 12-23%) and gross margin (down 3-16%) than halving agrochemical rates. *