Requirements of scientific advancement in understanding of processes regulating carbon (C) balance in terrestrial/semi-aquatic ecosystems, and the roles of the ecosystems in exchange of carbon ...dioxide (CO2) between atmosphere and terrestrial biosphere are well recognized. However, only limited studies have been conducted to assess the roles and potentials of wetlands, semi-aquatic ecosystems, in C sequestration. Out of 7% of world?s land is wetland. Thus, the study of C sequestration and the factors regulating it in a wetland will not only provide most needed knowledge for global C budgets, but also assess the possible integration of C sequestration in the objectives of creation and restoration of wetlands. The determination of stability of organic matter and assessment of roles of biotic and abiotic factors in regulating C exchanges between wetland ecosystems and the atmosphere may not only enhance the understanding of fundamental biogeochemical and eco-physical processes regulating C transformation in aquatic and terrestrial systems, but also help in the endeavors of reduction of anthropogenic CO2 in the atmosphere with long-term parity, and enhance the accuracy of global C budgets.
Forage quality and quantity from palatable grasses, like creeping bluestem Schizachyrium scoparium (Michx.) Nash var. polycladus (Schriber and Ball) Bruner (Syn S. stoloniferum Nash.), are limited, ...especially in winter when cows graze Florida range. We anticipated that N fertilizer (0, 40, 60, 120 kg ha(-1)), P (0, 25 kg ha(-1)) and K (0, 100 kg ha(-1)) would increase bluestem yield, tiller density, and forage quality. Within sample dates yield and tiller density increased linearly with N rate. For example 31 days after fertilization, intercepts for equations predicting yield were 319 kg ha(-1) and 124 m(-2) with coefficients of 1.2 and 0.29, respectively, where the independent variable is N rate. Over sample dates yield responses to N rate were quadratic and tiller densities were cubic. Reproductive tiller density was increased by N fertilization (1989 tiller density, no. m(-2), = 30 + 0.29N). Neither yield nor tiller density was affected by P fertilizer, but K fertilizer increased reproductive tiller density, hence fall yield. After 3 years of fertilization, N had negative quadratic and negative linear effects on yield and tiller density, respectively. Tissue N concentration in the fall was reduced with N fertilization because of increases in reproductive growth (1988 calendar 145 days postfertilization, g kg(-1) = 5.7 - 0.041 N + 0.00031 N(2)). Fertilization of creeping bluestem is not a recommended practice when bluestem is to be grazed in fall and winter.
Phosphorus fertilizer did not increase stargrass forage yield nor improved forage crude protein or forage digestibility when applied to an Immokalee fine sand soil (sandy, siliceous, hyperthermic ...Arenic Alaquod). Although the applied P improved forage tissue P concentration, most cattle producers routinely feed a balanced mineral salt which contains adequate P. Applied P caused a significant build-up of P in the Ap, E, and Bh horizons, increased soluble P concentrations in shallow and deep wells by 400% and 1500%, respectively, and in surface runoff by 50% and increased the potential for non-point source of P pollution. Gypsum was effective in eliminating P leachate from applied P into deep wells but was not beneficial for reducing P in surface runoff. Although promising in reducing total P in surface runoff, the long-term benefit of Ca-lime was not clear due to equilibrium effect.
Glycine (Neonotonia wightii) is an adapted and productive forage legume for the seasonally dry areas of the eastern Caribbean islands, but lack of seed availability has limited its use. Replicated ...field studies from September 1999 to April 2001 assessed fertilizer application effects on forage dry matter (DM) and seed yield of glycine var. Cooper. In September 1999, fertilizer treatments (FT) included 0 fertilizer (control), 56 kg ha"1 Ρ applied as triple super-phosphate: TSP, 56 kg ha"1 potash; K20, 28 kg ha"1 elemental sulfur; S, and 28 kg ha"' micro-nutrient mixture (2.4% boron, 2.4% calcium, 14.4% iron oxide, 6% manganese, 0.06% molybdenum, and 5.76% zinc). In September 2000, FT included a control, 56 kg ha"1 TSP, 56 kg ha"1 K20, and 28 kg ha"1 S. There was no effect of FT on either forage (3,100 kg ha"1) or pod yield (350 kg ha"!)in 1999. In 2000, however, there was a trend (P=0.10) for higher forage yield for FT. Response to S (forage DM yield of 3,945 kg ha"1) was better than other FT. There were also differences (P<0.05) in pod yield. A two-fold increase in pod yield with 56 kg ha"1 K20 (979 kg ha"') compared to the control (445 kg ha"1) was observed. Excessive rainfall in latter part of 1999 may have affected pod yield. The positive pod yield response to K20 in March 2001, and yield responses to sulfur justifies further evaluations.
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