COUPLING AMONG APPLIED, SOIL, ROOT, COMPONENTS FOR FORAGE CROP PRODUCTION

This analysis establishes linkage among (a) applied nutrients nitrogen (N), phosphorus (P), and potassium (K), (b) available soil nutrients, (c) root dry matter and nutrient content, (d) top dry matter and nutr ient content, and (e) leaf area and carbon dioxide (CO2) concentration . It was previously shown that (a) and (d) are coupled by logistic equ ations with a common response coefficient c between dry matter and pla nt nutrient uptake with each applied nutrient. As a consequence of the common c, it has been shown that dry matter and plant nutrient remova l are coupled by a hyperbolic equation. Furthermore, a model has been developed which includes N, P, and K as inputs. In the present work, ( a) and (b) were coupled by a logistic equation as were (a) and (c). It was then shown that plant nutrient removal was coupled to available s oil nutrients through a hyperbolic equation. The hyperbolic relationsh ip was also shown to link dry matter between roots and tops, as well a s plant N removal between roots and tops. As a consequence of the resu lts above, it was then concluded that root nutrient content is related to available soil nutrient through a hyperbolic equation. The detaile d mechanism of this coupling was not identified. Leaf area of soybeans followed a hyperbolic relationship with CO2 concentration in the cano py.