Owhakatoro Lands Trust is a Maori dairy farm supervised by Brett Petersen who is also a Kiwi Fertiliser representative. The difficult dairy farm is situated near Ruatoki, on the fringes of Te Urewera.
To winter 650 cows, 12 hectares of kale were grown. Sowing took place December 15, 2011, much later than planned for. The soil fertility requirements were determined by Perry Agricultural laboratories, and recommendations made by Kinsey Agricultural Services, both operating from Missouri, USA. We find their input critical to our success. Fertiliser used included DAP*, potassium sulphate, magnesium sulphate, sulphur, and up to six trace elements, depending on need. There were six paddocks involved, and three different soil tests to satisfy. One common fertiliser mix was used, trace elements excepted, for ease of management.
In early winter, the crops were measured and ranged from 16-18 tonnes of dry matter, a growth rate of 100kg/ha/day. An analysis of the kale revealed the nitrogen, at only 20 units was underdone. Add to that the late planting date, and the conclusion is the crop would have been better with an earlier planting date plus adding DAP* at the full rate recommended. Still, it was an excellent result costing only 3.7c/kgDM for the fertiliser inputs.
*DAP is used in situations where phosphorus is required in a hurry. We prefer Sechura RPR, but crops such as kale, grasses and others cannot access phosphorus from RPR in the first year, although legumes can. If phospate is already at good levels, Sechura RPR and similar can be used, as 80% of P comes from what is already in the soil and 20% from the applied product within 4 to 8 weeks of application.