Clover as a Cover Crop
A cover crop is any crop grown to provide soil cover, regardless of whether it is later incorporated as green manure or left as ground cover. Cover crops are grown primarily to prevent soil erosion by wind and water. Cover crops and green manures can be annual, biennial, or perennial plants grown in a pure or mixed stand during all or part of the year. In addition to providing ground cover which conserves soil moisture, they also help suppress weeds and reduce insect pests and plant diseases. Other benefits include reduction in ground, air and water pollution, improvements in soil health and in the case of legumes, nitrogen fixation in the soil. Many cover crops such as clover and grain provide high value forage for whitetails. Clover is a favorite food plot crop amongst whitetail enthusiast. It is safe to say that no other crop is so versatile and useful in agriculture.
Understanding Nitrogen Fixation
Clovers and legumes of all kinds fix nitrogen in the soil at varying rates. In reality it is not the legume plant that removes nitrogen from the air but Rhizobium bacteria, which live in small tumour like structures on the legume plant roots called nodules. Approximately 80 percent of the atmosphere is nitrogen gas (N2). Unfortunately, N2 is unusable by most living organisms. Nitrogen fixation is the process that changes the unusable N2 to useful NH4. This process in nature is only achieved by bacteria. These bacteria can take nitrogen gas from the air in the soil and transform it into ammonium (NH4), which can be used by the plant. This ammonium is the same form as in ammonium nitrate (34-0-0) and ammonium sulfate (21-0-0) fertilizer. Other plants benefit from nitrogen-fixing bacteria when the bacteria die and release nitrogen to the environment or when the bacteria live in close association with the plant. The nitrogen available to other plants does not become available until the legume crop is terminated. Clover residue incorporates easily into the soil with minimal tillage. The residue decomposes very rapidly, releasing part of the accumulated nitrogen for use by the following crop.
Inoculation- Cheap Insurance
Like other plants clovers need nitrogen to grow. They can use nitrogen from the soil in much the same manner as other plants. The difference between legumes and other plants is; legume roots seek specific strains of bacteria in the soil that will aid them in producing their own nitrogen. There are many strains of bacteria in the soil and only certain types can aid in the production of nitrogen. The helpful bacteria may be present in the soil, but without these bacteria the clover will not be able to produce its own nitrogen therefore added synthetic nitrogen would be required for growth. The legume would not develop the nodules and therefore would not produce or fix nitrogen into the soil for future crops. To guarantee the correct bacteria is present in the soil, plant seed is mixed with the appropriate bacteria contained in an inoculant.
Many times purchased seed arrives pre-inoculated. The useful bacteria in this pre-inoculant can die in time and in many cases you will find and expiration date posted on the seed tag. Many times it is cheap insurance to add fresh inoculant at planting time. Inoculant can be purchased at most seed sources or farm co-ops. Make sure you match the appropriate inoculant with the type of seed planted.