Zero till with a Moore Unidrill; note the independent discs and seed coulters (right) and press wheels on the rear (left) giving even depth of placement and good seed-soil contact. (Photo courtesy Agri-Linc.)
Direct drilling comes in two guises; drilling after a little cultivation (“min till” really), and what in the USA would be called “zero till”. Each has its own consequence in terms of weed control. Maybe I learned, years ago, most from a farms manager called Richard Noyce, he always had clean bottoms to his crops simply because, after harvest, he cultivated the surface several times to get weeds seeds to germinate, before putting the next crop in. The alternative of one pass to put the crop in does imply more work to do with selective herbicide – but that is probably going to happen anyway, so it is not an extra cost. Generally, in the hands of a sensitive husbandry man, zero till costs less and gives higher yields.
Good husbandry and using the right machinery is aiming at even depth of placement, good seed-soil contact, giving even emergence.
Bill Butterworth, Land Research Ltd, 20 August ‘18
Conventional, plough-based cultivations certainly have a place but with a high time and energy cost.
When not to direct drill? Some years, it is wet but the harvest still has to be got in and the result is ruts. They may have to be cultivated out but it is as well to remember that direct drilled soils are less likely to rut because of the resilience of organic matter and a “blocky” structure which distorts less under load, even when wet. Also, some soils naturally form pans which may need to be cultivated out. Last reason is to bury weed seeds – but try not to plough them up next year. Rotational cultivations may be the answer with a progression to long term direct drilling.
Persist with direct drilling next year wherever possible to help build up organic matter. (Actually it is more a question of avoiding the oxidation of organic matter from conventional cultivations which could be 35% pa while direct drilling will be as little as 10% or less.)
Bill Butterworth, Land Research Ltd. August 18