Soil nutrient and organic matter improvement and maintenance in a crop rotation system

I proposed to improve my crop rotation and fertilizer practices to better preserve organic matter and improve soil health. To do this, I needed to understand how my practices influence organic matter and nutrient levels over time. Dr. Evans and I looked at changes in soil organic matter, soil nutrient levels and plant nutrient content at specific points on the farm. These points were representative of my rotational and fertilizer practices. This helped us develop an understanding of how my system can be managed to maintain and possibly build organic matter, minimize erosion, and improve crop yields and quality.

The farming system described here incorporates these and other practices. It was developed with long term soil health as the central consideration.

The rotation sequence has undergone several modifications since its inception but has remained a four year system with both spring and fall plantings. Thus, it can be described as a "four year, eight stage" rotation. The eight plantings (stages) rotate yearly over four farm sections thru the sequence shown below.

fall --> spring
section

A vetch, winter rye mix --> mixed vegetables

B winter wheat --> cantaloupe / watermelon

C winter rye --> crowder peas

D mustard / garlic / onions --> buckwheat

SARE funding for this two year project began in the spring of 2001. Four fixed soil sample test sites were established for each farm section. 0-2 inch and 2-8 inch depth profiles at each site resulted in a total sample number of 32 for each sampling. Samples were sent for standard analysis including percent organic matter (%OM) to the soil test laboratory at Mississippi State University. Samples were collected in March and September of 2001, March of 2002, and March of 2003.

Two applications of approximately 6 tons of poultry litter each were made in 2002. An application in February included only 3 sections. For purposes of maintaining overall nutrient balance, a later October application was spread over all 4 sections. Future applications, when necessary, will precede the fall planting season.

Soil test results indicated a continuing improvement in all factors tested. The degree to which results can be attributed to either the rotation itself or to the application of poultry litter remains uncertain. Sample values of the two depth profiles, particularly pH and OM, may indicate improved soil tilth resulting from the rotation.