No Till Notes: 'Conservation agriculture'

During my conversation with Dr. Dwayne Beck a few weeks ago, Dwayne told me he had a couple of articles he wanted to email me to read about a systems approach to conservation agriculture. I really like the sound of conservation agriculture a lot better than I like no-till.

No-till began as a simple way to lower labor, machinery and fuel costs to produce crops. These were the reasons we looked to convert from conventional tillage winter wheat/summer fallow on our farm to no-till. We started much the same as many producers and simply replaced tillage with herbicides and continued in our winter wheat/summer fallow system. This was our model for implementing no-till.

Dr. Beck emailed me a couple of articles written by Dr. Ratten Lal. Dr. Lal is a distinguished soil scientist and director of the Carbon Management and Sequestration Center at Ohio State University. Dr. Lal makes the case for some limitations and concerns with simple no-till production and introduces the concepts for the adoption of a much more complete conservation agricultural system approach to production agriculture.

The starting point for Dr. Lal’s conservation agriculture system is no-till. Low soil disturbance is the beginning of adoption of conservation agriculture. This is only the beginning and many more steps other than no-till are needed to develop a truly sustainable and viable production system.

The second step in Dr. Lal’s model is the retention of crop residues. Leaving the residues attached and on the soil surface leads to soil and water conservation. The coat of residue armor protects the soil from wind and water erosion. The crop residues also lead to better water infiltration into the soil by protecting the soil surface from the power of rain drop splash, which can seal the soil and prevent water infiltration past the surface of the soil. The crop residues also lower the soil moisture evaporation rates, which are critical in our semi-arid environment. Crop residues also moderate the temperature at the soil surface. This is important in lower soil moisture evaporation and also providing a good environment for soil macro and microbiology at the soil surface. Providing good habitat for these microbes improves nutrient cycling of the crop residues. Crop residues are an important source of food for the microbes along with decaying roots deeper in the soil.

Dr. Lal’s third step in building towards conservation agriculture is the use of cover crops. We have all heard about the many benefits of cover crops. Dr. Lal points to the nutrient retention, weed control, inputs of biomass carbon and improved soil quality as benefits of cover cropping.

The problem I have with cover crops in our semi-arid environment is their implementation into our cropping system. We are limited in growing season and precipitation to make cover crops work successfully following our cash crop production on our dry land acres. We have begun using forage crops following winter wheat harvest on irrigated acres to improve the health of our soil. These forages will be grazed with livestock.

I see the implementation of these diverse cover crops on our dry land acres by planting diverse forage crops for grazing as an option. These diverse forage crops would achieve the many benefits of cover cropping and also add in the component of livestock grazing to profitably produce forage crops on our dry land acres.

Forage crops following winter wheat production on our irrigated acres and as a component of our dry land crop rotation are viable options. Adding these forage crops will help us achieve Dr. Lal’s third step in moving towards conservation agriculture. Next week, I’ll look at additional steps required to achieve a complex conservation agricultural system rather than simple no-till.