MANURE AND GRASS-FARMING

Firman E. Bear, Carl B. Bender

THE POSSIBLE savings in soil fertility in the best developed systems of livestock farming are such that they merit much more consideration than many farmers give them. If all the manure is carefully cared for and applied to the land, the losses of fertility constituents from the soil of a dairy farm are so small that they can be readily and cheaply made up.

Three important means of compensating for such losses exist : The growing of legumes, the purchase of extra feeds from which additional manure can be produced, and the supplemental use of fertilizers to balance the nutrient supplies in the soil.

Where large acreages of legumes are grown and feed purchases are high, the supplemental fertility needs can often be met by the use of liming materials and some form of phosphate. If the farmer is aiming for maximum efficiency in the use 9 of his land, however, considerable amounts of complete fertilizer will be required to supplement the manure. This is especially true if the farm is located in an area where the Climate naturally favors grasses.

When all factors, including protection against erosion losses and reduction in the rate of soil exhaustion, are taken into consideration, grassland agriculture is found to offer a unique opportunity for long-time, dependable profits. Some idea of the possible soil-fertility savings in such a system of farming is presented here.

An experiment at the New Jersey Dairy Research Farm at Sussex indicated a manure production of 21 tons a year for a 1,300-pound Holstein cow. Of this, 25 percent was urine and 75 percent feces. Each ton of the mixed excreta contained 9 1/2 pounds of nitrogen (N), 3 pounds of phosphoric acid (P₂O₅), and 8 of potash (K₂O).

It is apparent that the tonnage of manure from a dairy herd is large. But cow manure is a relatively dilute fertilizer that requires economy in handling. Unless its fertility is conserved and the handling costs are kept low, the profit potentialities from its use will be largely dissipated.

In this test 70 percent of the nitrogen in the feed, 63 percent of the phosphoric acid, and 86 percent of the potash were found in the manure. The unrecovered portion was contained in the milk and in the calf that was being formed. Such losses or differences can readily be compensated by the purchase of extra grain feeds. By that means, however, the fertility of a grassland farm can be built up only at the expense of a grain farm farther west.

But even for the farmer who feeds only what his own fields produce, the possible fertility economy in dairy farming is apparent. The 30-percent loss of nitrogen can be made up by growing legumes. The nitrogen of the harvested part of a clover crop is probably clear gain, the roots and stubble containing about as much of this element as the plant has taken from the soil. On this basis a 3-ton crop of clover or alfalfa hay, or its equivalent in pasture or silage, collects around 120 pounds of nitrogen from the air. Assuming a 70-percent recovery in the manure, this means a gain of 84 pounds of nitrogen per acre of clover grown and fed on the farm.

Manure is such a valuable and effective crop-producing agent that farmers can afford to put considerable effort and expense into protecting it against loss of its nutrient elements.

The first essential to this end is that all the urine be saved, either by the use of absorbent bedding or by draining it into a closed cistern.

A second need is to avoid loss of nitrogen as ammonia from stored manure. Such losses can be controlled by using superphosphate as an ammonia-absorbing agent and by keeping the mixed solid and liquid manures moist and well-compacted, as by the tramping of animals.