Model Analysis for Response of Dwarf Elephantgrass to Applied Nitrogen and Rainfall

Abstract

In numerous articles, the extended logistic model has been used to describe response of annual and perennial crops to applied nutrients [such as nitrogen (N), phosphorus, and potassium]. The model accounts for coupling between dry matter and plant nutrient accumulation by way of phase relationships. Factors such as water availability and harvest interval (for perennials) can be easily incorporated. The model is well behaved and is simple to use for estimation purposes. In this article, response of a bunchgrass to applied nitrogen and rainfall is discussed. Field studies in Florida lead to similar parameter values as those in Texas. Linkage of lower and upper limits on plant N concentration is explained.

Estimating Seasonal Nitrogen Removal and Biomass Yield by Annuals with the Extended Logistic Model

“…The b N parameter is affected by changes in plant population [11] and is also influenced by crop type [8] , [25] . The remaining parameter, A N , is a linear parameter that is affected by the various environmental conditions, the crop type, the soil type, and various management practices [5] – [20] . Given Eq.…”

“…The logistic model was extended to include seasonal plant N uptake (removal from the environment) dependence on applied N by forage grasses [4] and then for annuals, like corn [5] . The ELM is a five parameter, non-linear, parametric model that is capable of describing the seasonal biomass yields, N uptake, and N concentration with respect to applied N. Work conducted over the years has indicated that the ELM can effectively describe both annual [6] – [11] and perennial [8] , [12] – [20] crops, for a wide range of nutrient inputs.…”