Sustainable livestock production depends on reliable forage resources that maintain animal health and fecundity. Temporal and spatial variation in forage production in most range and pasture systems are closely linked to the timing and amount of precipitation.
Grazing management decisions are often based on a producer’s knowledge of past or average forage production levels with little certainty that sufficient precipitation will fall in time to produce what is anticipated. The cumulative effects of inaccurate grazing management decisions include poor Average Daily Gain in livestock, loss in soil fertility, increased rates of soil erosion, and establishment of weeds. Thus, development of a rainfall and forage production index that accounts for temporal and spatial patterns in precipitation inherent to a given locale will greatly improve the management decision process.
The purpose of this study was to quantify the relationship between local precipitation patterns with forage production in major rangeland ecosystems commonly grazed in Hawaii. Fifteen weather station and forage production exclosures were established across the state. Weather data were recorded hourly and forage production estimates were collected quarterly from all exclosures for three years. Regression analyses were used to develop the Hawaii Rainfall and Forage Production Index that will be useful for forecasting forage production and suitable stocking rates, drought planning and mitigation, development of prescribed grazing standards, establish soil erosion mitigation standards, and planning range improvement projects.
As a direct output of this project we have developed a decision support tool that is available online at the Hawaii Rangelands website (http://rangelandsgateway.org/hawaii). This tool will help you to evaluate forage availability over a period of time given current rainfall totals and the number of grazing animals. In the face of developing drought conditions the tool will help you make critical management decisions to avoid overgrazing drought stricken pastures. In addition the tool can be used to estimate the amount of forage that will be produced over a 30 day period given a certain amount of precipitation. Again, helping you make pro-active grazing management decisions. We invite you to view and use the tools and as always contact us if you have any questions.