Forage budgeting is balancing forage production and use. The three main types of forage budgeting are livestock carrying capacity budgeting, winter feed budgeting, and growing season pasture production budgeting.
Livestock carrying capacity budgeting
Whole-farm forage budgeting to determine the farm's livestock carrying capacity is done by the Natural Resources Conservation Service to evaluate the safe stocking level of livestock on the farm. Forage budgeting also looks at potential changes in stocking level because of improved forage management. Most farmers arrive at an estimate of their farms' carrying capacity through years of experience, including some accounting for risk because of drought and wet weather effects on pasture and hay production.
Winter feed budgeting
Livestock producers budget winter feed by maintaining (on paper or in their heads) an inventory of the hay supply on hand, which is tied to an estimate of the hay required to feed the farm's animals. The producer decides whether feed supplies are in excess or deficit of the herd's need. The farmer then knows if hay can be sold or must be purchased, or if some animals that normally would be kept need to be sold.
Budgeting pasture production over the growing season is not as well managed by many livestock producers as the previous two forms. Often, pastures are undergrazed in the spring and overgrazed in the summer and fall. This results in less than optimal animal performance because of overmature forage in late spring and inadequate forage availability in the fall. The pasture plants may be weakened by overgrazing since the reduced leaf area may not intercept enough sunlight for adequate root growth.
Research at WVU and other universities has shown that if pasture is grazed too short, animal performance is reduced. WVU research on continuously grazed, mixed short-grass pastures shows that the minimum pasture height for good animal performance is about 3 inches for the calf in a cow-calf system and 3 to 4 inches for a growing steer (Figure 1). When pasture height is above the 3- to 4-inch level, animal performance may decrease because of reduced forage quality, if the excess spring growth is not controlled by haying part of the land or using a variable stocking rate.
The growth rate of pasture varies over the season (Figure 2). Managers must vary either the acreage grazed or the number of animals on the pasture as the season progresses, if optimum forage and livestock management is to be achieved. Another option is stocking for the slower growth in August and clipping the excess pasture growth in June, to maintain quality. This waste of forage is sometimes the most economical approach where pasture and hay land are not situated next to each other. If none of these management practices is followed, animal performance will be reduced.
If overgrazing occurs, soil erosion increases, resulting in a loss of topsoil, soil fertility, and future productivity of the land. The eroded soil will also reduce water quality for people living downstream from the mismanaged land.
Forage and livestock production can be optimized using rotational grazing with a hay field buffer. The hay field buffer is where part of the land is harvested for first-cut hay, then brought into the system for grazing the hay aftermath. Under rotational grazing, a short grass (bluegrass-white clover) pasture should grow to 4 to 6 inches high, then grazed to a 1- to 2-inch stubble. This results in an average pasture height of 3 to 4 inches during the grazing period which is optimum for animal performance. This management is also beneficial for clover production in pasture. Under rotational grazing, tall grass stands such as orchardgrass-red clover should grow to an 8-inch height, then grazed to a 2- to 3-inch stubble.
When drought reduces the pasture growth rate and animals begin to graze the pasture shorter than what is good for the pasture and animals, start supplemental hay feeding. Move the animals to a field that needs the fertility supplied by the manure from the feed. Above all, protect the grass over most of the farm so it will stay healthy for growing once the rains return. When this management is followed and once moisture returns, the grass will grow up to twice as fast as it would if the livestock are allowed to graze it into the ground. If fertilizer is applied also, the growth rate may be even higher. In 1999, managers using these practices did feed hay much of July, but got the cows back on quality pasture in August and kept them on pasture until the end of December.
Budgeting pasture growth over the year--by using rotational grazing and hay field buffers, controlling grazing by using proper pasture height guidelines, and not overgrazing during dry weather--is the keys to optimizing forage and livestock production and reducing the risks and damage from drought.
Figure 1. Expected effect of pasture height on calf growth in a cow-calf system.
Figure 2. The effect of the date and year on pasture growth rate on fertile soil with good water-holding capacity.