Transitioning from grazing pasture to horticultural production can be challenging in the first few years. Weeds and a buildup of pasture weed seed in the soil is the primary struggle, and management will be dependent on your crop variety being planted, size of area to be converted, planting layout of crop, and if conventional or organic growing is being used. Regardless, the initial conversion requires the removal of as much weed potential as possible.

The first step in conversion is pasture eradication. When converting large areas for commercial production, use of a non-selective herbicide is recommended. Starting this process early, ideally more than four weeks before planting, is important to ensure there is enough time to eradicate at least the first flush of weeds before planting. More time can give you further opportunities to remove even more weeds. In smaller-scale organic systems, the use of large covers to block light from the area can be used. A black plastic cover, which generates heat, will also help to kill off the plant material.

After eradicating the pasture, shallow cultivation with a power harrow or rototiller will expose buried weed and pasture seeds to the surface, allowing them to germinate. Allow for fourteen days for seed germination, maintaining observation of the area to eradicate any weeds that may turn to seed. The purpose of this is to allow as many of those exposed seeds to germinate as possible before following with a non-selective herbicide (or coverage) to kill off this flush of weeds before they develop more seed. If you have given yourself enough time and have a heavy weed load, this process can be repeated prior to deep cultivation.

At this point you are ready for deep cultivation prior to planting. Here I would recommend the use of a subsoiler followed by a rotary hoe, with an aim at creating a well cultivated clump-free soil.

You are now ready to plant your crop. Keeping track of planting dates and germination time is important. If growing conventionally, you can use this data to fit in an extra spray three to four days prior to germination of your crop if planting by seed. In organic systems you can re-cover the whole area to stop germination of any remaining weed seeds and uncover three to four days before your crop seeds are due to germinate.

When planting seedlings it is recommended to use a pre-emergent herbicide (check with your crop type to find an appropriate one) as a preventative method and allow for crop growth to ideally outpace and shade weeds that come up amongst them.

This article is part of our Branching Out project

Since 2020, Branching Out has identified, investigated, and validated over a dozen diversification opportunities and high-value food and fibre ventures for the region. The project’s vision is to ensure the long-term sustainability and resilience of the food and fibre sector in Taranaki and the communities it supports. Besides hops, other crops of interest include gin botanicals, hemp, medicinal plants, and grains, legumes and vegetables for incorporation in a sustainable crop rotation.