Why soil health is important, and what farmers do to improve it

Itook a ride in the country this week to see what was happening and was surprised as I drove 24th Street west to Somerton Avenue, south to County 16th, east to Avenue D and back to 16th Street, where I saw acres and acres of fields lying unplanted.

While affected by two years of covid and the Colorado River shortages, the fact that fields hadn’t been mulched, much less listed, sprinklers strung or planted was amazing. Because of the uncertain economic times and disruption to “normal” life, the agricultural industry is suffering like the rest of the country.

Since our winter vegetable industry depends on knowing where the product will go before planting, changing conditions for growers, particularly concerning water, will definitely affect crops to be grown.

If fields are not being planted early, farmers have an opportunity to look at improving their soil health. Our Yuma County soils do not improve by fallowing and it is important that irrigation continue to make sure soil salts continue to be moved below the root zone of the vegetable crops to be planted.

Historically, the summer crops are Sudan grass for hay and seed, cotton and seed crops. Legumes such as sesbania, annual ryegrass, barley, vetches, field peas or clovers can be used as green manures, which are crops that are turned into the soil before maturity to improve the growth of following crops. The benefit from green manure crops is to increase soil organic matter levels, reduce soil compaction and enhance crop yields.

Organic matter plays a role in aggregate stability. The stabilization process is accomplished mainly through the byproducts of organic matter decomposition. Water infiltration into a soil and its movement through the soil layers is greatly enhanced by organic matter in the soil.

Many of the green manure crops are also nitrogen fixing crops, meaning that nitrogen is taken from the air and stored in the plant. After the green manure crop is tilled into the soil, the plant material breaks down, nitrogen is released and becomes available to the growing cash crop.

Yuma County soils are extremely low in natural organic matter. While some of the Midwestern soils contain as much as 5% organic matter, Yuma soils contain less than 0.5% organic matter and it needs to be renewed every year through use of composted manures, green manure crops or tillage of crop residues into the soil.

Organic matter also improves aeration of the soil. Plants need as much air as they need water and as the organic matter breaks down, it leaves holes between the soil particles called pores. It is through these pores that both air and water travel into the soil.

While there is an investment by the grower in seed, labor and equipment time, the benefits of growing green manure crops are invaluable to the health of the soil.

An alternative to plant material is the use of composted manures. Commonly used manures are cattle and chicken.

These products have to be specially treated to make sure any pathogens, weed seeds or diseases are killed prior to use on fresh vegetable fields.

The concern with manure is food safety and strict standards are followed in the use of them.

Fresh vegetable production is a continually changing industry. Meeting customer desires for the variety, quantity and quality of products is a constant priority.

I am looking forward to seeing the usual colorful patchwork quilt of our multiple vegetable crops in the fields later this fall.