The Community Post

Hoorman: Soil Conditions

- James Hoorman

Some cooler temperatur­es are coming and some rain has occurred. Most farmers are hoping for more rain to get their crops out of the ground and growing. One thing, where ever the soil had higher amounts of soil organic matter (SOM), the crops emerged and are growing much better. Every 1 percent SOM holds about 0.5 to 0.8 inches of rain, which helps crops germinate and grow until they get their roots establishe­d. Building SOM requires getting more roots in the soil. No-till and cover crops are two ways to build SOM and reduce adverse weather.

As wheat harvest approaches, farmers may be considerin­g double cropping soybeans. In a dry year, soybeans may not be the best option, but letting wheat stubble remain bare promotes weeds. Many cover crops can grow and thrive with little soil moisture including buckwheat, cowpeas for nitrogen, and teff (forage crop). Diverse cover crop mixtures help each germinate and get needed nutrients. Planting cover crops after wheat is a safer bet when moisture is lacking.

The late David Brandt in his last interview with No-till Farmer gave several tips on using cover

multiple species of cover crops is the easiest and fastest way to improve SOM.

The third option is to grow and capture nitrogen (N). Many clovers and legumes are capable of producing from 100#-200# of nitrogen. Hairy vetch, common vetch can add 200# N, cowpeas winter peas, and sweet clover up to 150#N, and crimson clover, white clover, Sunn Hemp up to 100# N. After a dry year, excess unused N can be captured by grass cover crops like cereal rye, annual rye grass, barley, teff, oats, and brassicas like radish, kale, and rape. Capturing N and building SOM can be as valuable as producing double crop soybeans in a dry year. Unfortunat­ely, growing soybeans without a carbon source (grass) tends to make your soil hard and less productive.

Brandt’s fourth option was to experiment with reducing crop inputs especially harmful herbicides by using a crimper crop roller. Glyphosate (Roundup) is a chelator of many beneficial micro-nutrients. A mechanical way to terminate cover crops is to use a crimper to roll cover crops flat to terminate cover crops. Three cover crops that can not be terminated with a crimper are annual ryegrass, red clover, and alfalfa. Most cover crops crimp the best when they start to bloom or come into head, which maximizes root developmen­t and nitrogen formation on legumes and clovers. If it gets too dry in the spring, terminate early with a burndown herbicide. Farmers have several new and old burn down options that avoids glyphosate use (Harpe, Sharpen, Liberty, 2-4D, Gramoxone (paraquat), Reviton).

A fifth option is to try inter-seeding cover crops into existing crops. In the fall; farmers are using drones, airplanes, helicopter­s, and highboy applicator­s to seed cover crops before the main crop is harvested. At least 1-2 inches of rain is required to get the cover crops to thrive before winter sets in. Most cover crops need a minimum of 60 days growth to survive the winter. Inter-seeding cover crops into corn, between the rows is another option, but not recommende­d in a dry year. The best time to inter-seed in corn is when the corn has four to no more than 5 true leaves (V4-V5). If its really dry, the cover crop either will not germinate, or if the dry period occurs later in the summer, sometimes the cover crop can compete for moisture. Timing and weather conditions are critical when making this decision. These are all tips for making soils more resilient to adverse weather conditions.

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