Green manure is composed of organic matter which includes the
sacrificed cover crop. Green manure reduces runoff and erosion
while improving the degree of soil aggregation. Green manure is
best used to increase the organic matter content of the soil,
contributing essential elements to the soil.

 Mulch is composed of the killed winter cover crop, compost,
leaves, residues, as well as inert materials such as sand and
pebbles. Mulch prevents water loss from the soil by evaporation
and keeps the soil moist and cool. Decaying mulch can serve to
hold more plant nutrients as well as the addition of nutrients to
the soil.3

 The use of a legume as the cover crop has certain benefits to
the soil and crop which follows. The legume has a symbiotic
relationship with N-fixing bacteria. The bacteria live on the
plant's roots, absorbing the vital photosynthate (i.e. glucose)
that it requires from the plant, while converting the N in the
atmosphere (N,) into NO, or NO2, the sources of essential N for the
plants. The cover crop crimson clover (Trifolium incarnatum L.) is
a legume, although rye (Secale cereale L.) is not. Rye has the
benefits of making an excellent mulch.

 Nitrogen is the single most important fertilizer element and
is required in the largest quantities for crop growth.4 Legumes
are one source of organic N that can be used as a cover crop to be
sacrificed for corn in a double cropping system. A second source
of N is inorganic N fertilizer which is applied in the form of
ammonia NH, in the compounds of NH4NO3 or NH4SO4. However, there
exists a limit to how much N a crop can absorb and utilize. Too
much N may induce K* deficiency, a vital mineral needed for
photosynthesis and proper regulation of turgor pressure and
stomata.5 Skeletal soils, like those in Florida, need heavy inputs
of N, thus increasing the demand for expensive inorganic N
fertilizer. A cover crop must be utilized to offset the need for
N. The corn crop has a sufficient level of N if the concentration
in the ear leaf at early silking and tasseling is between 2.70% and
4.0% N.6 A proper balance between the right cover crop, the right
manipulation of the cover crop, and the right amount of inorganic
N fertilizer will lead to the ideal conditions for corn growth at
the lowest cost.

 In order to discover the most efficient methods to grow the
best crop, a number of null hypotheses have been created.
 I. The cover crops of crimson clover or rye will not satisfy
the N requirements of corn, nor affect the ear leaf area, ear leaf
weight, or ear leaf N concentration.
 II. Inorganic N fertilizer will not be needed in any amount
to meet the N requirements of corn (under the influence of the
cover crops), nor affect the ear leaf area, ear leaf weight, or ear
leaf N concentration.