Organic Farm School explores reduced tillage strategies

The Organic Farm School (OFS) is partnering with soil scientist Doug Collins to trial ways to improve the soil the through minimizing tillage on our farm. Doug Collins is an Extension Faculty with WSU’s Small Farms Program and an affiliate faculty with the WSU Department of Crop and Soil Sciences.

For 2017, the OFS will be planting winter squash in a trial comparing strip-till, no-till and full-till soil preparation. In the strip-till and no-till plots, cover crops are now growing that will be killed through flail mowing, leaving a thick weed-suppressing mulch on the soil surface. Over the course of the season, we will then evaluate a wide range of soil quality parameters including earthworms, microbial biomass, greenhouse gases, nematodes, bulk density, soil compaction, infiltration, soil temperature, soil moisture, light penetration, and the weed seed bank. Weed pressure, time spent weeding, crop yield, fuel usage and cover crop biomass will also be evaluated.

Doug Collins has been researching these strategies for several years now and we look forward to helping continue his work and answer the important questions this work brings up such as,

1.     How does reduced tillage affect nutrient cycling and fertility management?

2.     Does reduced tillage improve water use efficiency?

3.     Which cover crops, mixes, and termination strategies perform best?

4.     What specific challenges and opportunities do continuous reduced‐tillage present?

5.     Which implements and strategies are most effective to manage residue in strip‐tilled ground?

6.     What strategies improve transition to reduced tillage?

So far, some of Doug Collins key findings include that tillage reduces earthworm populations while increasing evaporation and soil carbon dioxide emissions, all items we’d like to turn around. Conversely, tillage helps reduce compaction, increases soil temperature and manages weeds, so in moving to alternatives we need to address the lack of these benefits.

One strategy is to create a hybrid system (strip-till) where narrow strips for planting are tilled while the rest of the area remains undisturbed.  In addition, while the terminated cover crops act as a mulch preventing weeds, they usually do not provide complete control. Normal weeding equipment cannot work through these mulches so Doug Collins has built and will bring a high-residue cultivator that can cut through and work under the mulch.

The OFS is excited to be doing this work that focuses on how farming can contribute to reversing climate change, improve our soils and make farms more efficient simultaneously. We are grateful to Doug Collins for including us in this project and look forward to sharing our trial results this fall.

Checking seed depth after the first pass of the seed drill.

Checking seed depth after the first pass of the seed drill.