Great Bend Tribune
Part I - Published March 1, 2020
The Drought Monitor showed marked improvement for all of central and even most of western Kansas. Northwest Kansas, except for the extreme corner which is abnormally dry, is out of dry conditions. The area of dry and moderate drought retreated to the west of Ford County and there is only a small area of severe drought along the Colorado border. The six to ten day outlook (March 4 to 8) has below normal precipitation and normal to above normal temperatures which bodes well for the wheat crops emergence from dormancy. Looking out eight to fourteen days (March 6 to 12) indicates below normal precipitation and above normal temperatures. This should allow for the application of nitrogen and herbicides for the wheat crop as many producers are behind with the past few weeks weather. With the moisture present as of now, this is again good for the 2020 wheat crop and for preparing to plant the 2020 corn crop. The thirty day outlook is for below normal temperatures and a coin flip for precipitation with the ninety day outlook basically near normal for both. Today, let’s briefly discuss an extremely hot topic in production agriculture – cover crops.
First, for context, let’s define cover crop and green manure. A cover crop is defined as “plants that are planted to cover the soil rather than for the purpose of being harvested. They manage soil erosion, soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in an agroecosystem.” A green manure is defined as “A crop grown and plowed under for its beneficial effects to the soil and subsequent crops, though during its growth it may be grazed. These crops are usually annuals, either grasses or legumes. They add nitrogen to the soil, increase the general fertility level, reduce erosion, improve the physical condition of the soil, and reduce nutrient loss from leaching. They are usually planted in the fall and turned under in the spring before the summer crop is sown and while green.”
Cover crops and green manures are hardly a new topic, starting to receive renewed interest back in the early 1980s. This coincided with interest in “organic” or “sustainable” production of crops and the desire to decrease/eliminate the use of synthetic pesticides and synthetic/inorganic fertilizers. Keep in mind that a green manure can be a cover crop but the major difference is that a green manure is worked into the soil while actively growing so using a green manure doesn’t fit into a no-till system. The cover crop is terminated in time for the planting of the succeeding crop, normally with enough time to prepare for the harvested crop. While normally planted in the fall, there are also many planting summer cover crops. And while initially geared toward “organic” farming operations, they are used in more and more convention operations.
Legumes (clover, vetches, peas, etc.) are promoted as they fix nitrogen which can be broken down and provide “free” nitrogen. Non-legume broadleaves such as brassica species and annual grasses are also often used. While they don’t provide as much “free” nitrogen, they do provide organic matter and a carbon/nutrient source for a healthy microbial population. Next week – the advantages and disadvantages of cover crops.
Part II - Published March 8, 2020
The Drought Monitor continued showing the marked improvement for all of central and even most of western Kansas. The dry conditions this past week should have allowed many producers to make progress with covering winter wheat fields. The six to ten day outlook (March 10 to 14) has above normal precipitation and temperatures which bodes well for the wheat crops continuing progress. Looking out eight to fourteen days (March 12 to 19) indicates above normal precipitation and well-above normal temperatures. The thirty day outlook is for equal chances of above or below normal temperatures and a coin flip for precipitation with the ninety day outlook basically near normal for both. Today, let’s continue discussing a hot topic in production agriculture – cover crops and their potential benefits.
- Benefit number one is, by keeping the soil covered with living vegetation and an active root system below ground, the virtual elimination of wind and water erosion. Keep in mind that even under the best of conditions it takes hundreds of years to produce an inch of topsoil. In addition to keeping soil in place, a cover crops keeps nutrients in the soil and minimizes nutrient loss in runoff or from moving into groundwater.
- Cover crops provide a nutrient and carbon source for soil microorganisms which increases biological activity, nutrient cycling, and builds up stable organic matter over time – humus. Increasing organic matter also helps by increasing the soils water and nutrient holding capacity while also decreasing a soil’s bulk density, improving soil structure, and improving soil tilth. The surface cover also aids in infiltration while below ground macroporosity is improved, especially when legumes are part of the cover crop mix and tillage is minimized.
- A cover crop with legumes, nitrogen fixing plant-bacteria association, such as peas, clovers, and vetches can contribute “free” nitrogen to the soil for succeeding crops. This can be significant depending on the amount of growth before termination.
- Weed control is also another benefit when things work out. Any actively growing crop is the best weed control and since cover crops are drilled, they can be an excellent way to smother out weeds and decrease the need for herbicides.
- Certain types of cover crops with aggressive taproots such as vetches and tillage radishes can be valuable in helping to break up hardpans and compacted layers in soils. This improves soil drainage, rooting depth for crops, and improves aeration.
- Typically to store moisture, producers in drier climates would fallow – leave the soil devoid of vegetation for a growing season to accumulate soil moisture for the next crop. Some fallow would be for a shorter period of time, say between wheat crops of fall-harvested crops. Initially, vegetation was controlled by tillage then herbicides became available so this could be accomplished chemically or by a combination of both methods. However, even under the best fallow technique water stored would only be around one-third of the precipitation received. Much research in places like northeast Colorado has found that except under the most severe drought, cover crops were more effective than fallow. In addition the biological activity was significantly enhanced.
Next week – the potential disadvantages and challenges of cover crops.
Part III - Published March 15, 2020
The Drought Monitor continued showing the marked improvement for all of but portions of Southwest and Northwest Kansas. Wheat is showing the benefits of this moisture and warmer temperatures. Producers continue to make progress with covering winter wheat fields with nitrogen and herbicides. This week promises to be unsettled with normal to below normal temperatures and moisture. The six to ten day outlook (March 18 to 22 has above normal precipitation and normal to above normal temperatures. Looking out eight to fourteen days (March 20 to 28) indicates above normal to above normal precipitation and normal to below normal temperatures. The thirty day outlook is for above normal temperatures and below normal precipitation with the ninety day outlook basically near normal for both. Today, let’s finish discussing a hot topic in production agriculture. We have covered what they are and their potential benefits. Now – what are the potential drawbacks?
- If you really commit to planting cover crops, including legumes such as pea species and vetches, it can be pricy, really pricey. Clovers can help and aren’t quite as expensive, however, they typically don’t provide as much bang for the buck as the previously mentioned legumes. This is why some are planting more conventional types such as rye. On the plus side, there should be some help available from the USDA to cover costs, especially in certain areas such as areas with sandier soils.
- For those crops overwintering such as vetches, peas, and winter grass species, they must be terminated. This can be done chemically, mechanically through tillage, or a combination of both. Along with this is needing to determine when to terminate. The longer the growing period, the greater the potential benefits. However, a producer needs adequate time to prepare for the succeeding crop and doesn’t want to deplete the soil of moisture by waiting too long. There are clever ways to avoid this. For example, if you can plant spring oats earlier in the fall so they have adequate time to produce top and root growth (remember they tolerate some fairly cold air temperatures), the oats will normally die, winter kill, and you don’t have to spray or till.
- Rotational considerations also must be considered to avoid potential insect and disease pressure for succeeding crops. Also of importance is examining your herbicide plan to insure your herbicide history won’t negatively affect your cover crop. Ideally, if you are committed to cover crops, over time the need for herbicides can diminish.
- To obtain the best, long-term benefits from cover crops, a producer should eliminate tillage. This isn’t feasible for some producers and more difficult for certain crops when planting into heavy residue.
- It can be difficult to get you landlord and sometimes your banker onboard.
- Finally, rain, or rather a lack of rain can greatly reduce the growth of the cover crop and the succeeding crop.