Capturing the nitrogen accumulated in the soil in the wake of winter grazing, and using it to grow high-quality feed in spring, is good for business and the environment.
Early results from the first year of a Ministry of Primary Industries Sustainable Farming Fund (SFF) project, which is looking at using catch crops to mitigate nitrate (N) leaching during winter forage grazing, has shown that the inclusion of a catch-crop (such as Intimidator oats) can generate a gross profit of $1800/ha (DM valued at 20c/kg). That was from a 12t dry matter (DM) per hectare Intimidator oats crop sown into a grazed kale paddock in mid-July and harvested on November 20.
In this particular example, the oats pulled up 223kg N/ha, N that would have potentially been lost to the environment.
Peter Carey, a field research scientist with Lincoln Agritech, who is carrying out the three-year SFF project, says they have three trial sites in Canterbury and two in Southland, all on commercial farms.
Last year four out of the five trials were very successful which reinforced the value of catch crops as part of a crop rotation.
“Catch-crops increase the efficiency of the operation by retaining N in the system that farmers would otherwise have waved goodbye to.”
Peter says while they are comparing Triticale and Italian ryegrass as part of the catch-crop trial, oats are ideal because they are more winter active, and therefore are growing when the soil microbes start turning the ammonium from the deposited urine into nitrate, the most easily leached form of N.
The whole process is temperature related.
“Once the soil temperatures warm up enough to start the oats growing, it is exactly the same time as the nitrification process kicks into gear.”
Oats, with their larger seed, are well suited for drilling in low soil temperatures. They are also robust and have deep roots to capture the soil N.
Peter says one of the challenges with catch-crops is having the ability to get the crop established into winter-wet soils. Last winter was particularly favourable, but comparisons between conventional cultivation and direct-drilling (with minimal passes) showed that while initially the conventionally worked crops looked to be ahead of the direct-drill treatments, by harvest there was little difference in yield and the cheaper tillage costs of direct drilling more than compensated.
Vincent Luisetti says recent Foundation for Arable Research trials showed that Intimidator Oats produced an average of 17.8 tonnes of dry matter per hectare, which would generate an even greater gross margin for growers.
The other advantages of Intimidator oats include their frost tolerance (due to large thick stems) and high protein content.
Luisetti Seeds is proud to be a funding partner in this SFF trial.
On-going dry weather could mean tight feed supplies this year, so a forage crop which generates high quality feed in winter and spring will...