Manure: A Wartime Fertilizer

by R.B. Child
published by New York State College of Agriculture, Cornell University, Ithaca
cover photograph is from New Idea, Inc.

With fertilizer prices rising, it is good business for farmers to make the best possible use of the plant food already at hand in farm manure. The 26 million tons of manure produced annually on New York farms carries twelve times more nitrogen than was sold in commercial fertilizers in the State in 1940.

Two Birds With One Stone

Thousands of tons of nitrogen normally used in commercial fertilizer are going into munitions. Therefore, there is a serious shortage of fertilizer nitrogen, which is essential for increased production of fruit and vegetables. By doing a better job of handling manure, the dairy and general livestock farmer may reduce his purchases of nitrogen to the minimum, and thus release appreciable amounts of this plant food for fruit and vegetable farms. The results should be two fold:

1. Increased production of milk and meat.
2. Increased production of fruit and vegetables.

In addition to nitrogen, phosphoric acid, and potash, manure contains considerable calcium and smaller amounts of minor elements. The amounts vary with kind of animal, composition of feed, age of animal, milk production, and individuality of the animal. For example, about two-thirds of the nitrogen and one-half of the phosphorus carried in the ration of a well-fed, heavy-producing dairy cow is excreted in manure. A well-fed two-year-old steer excretes almost 90 per cent of the nitrogen and phosphorus consumed. The organic matter and bacteria contained contribute benefits beyond those of the plant food.

Some Losses Inevitable

Large amounts of nitrogen, potash, and organic matter are lost in any system of handling, and appreciable amounts of phosphorus also disappear. The most serious losses are due to failure to save the liquid portion, to passing off of nitrogen into the air as ammonia, to leaching and decomposition in piles, and to excessive applications.

Better Use of Farm Manure

To some men “better use” means plastering a few acres for bumper crops near the road. To others, it means economical crop production, or getting the most out of each ton of manure.

Nitrogen costs more per pound than does phosphoric acid or potash. All three elements are essential to plant growth. The solid and liquid portions each carry about one-half the nitrogen contained in manure. Therefore, every effort made to prevent nitrogen losses also conserves phosphoric acid, potash, and organic matter.

Recommended Practices

Several practices have proved sound by field-crop experiments. Some of these experiments have been conducted for as long as 40 years.

Spread Manure Thinner Than Usual and Apply It More Often in the Crop Rotation

In the entire field of experimental and practical crop production, no other fact is as conclusively proved (and so generally disregarded) as lower applications per acre give greater returns per ton of manure.

Most dairy farmers underestimate the weight of a load of manure. Twenty-five 1200-pound milch cows and seven yearlings on common rations produce about 1.3 tons of manure daily, not including bedding. With the usual amount of bedding, the thumb rule estimate of a ton per load is too low.

At the Cornell University dairy barn, where 700 pounds of wheat straw is used daily for 100 cows, the strawy manure averages 38 pounds per cubic foot as taken from the barn. A spreader with a rated capacity of from 60 to 70 bushels, heaped up a foot above the box, holds 1.3 tons of this strawy manure.

For a 10-ton application, this 1.3 ton load should cover a 7-foot spreader swath all the way across a 50-rod field.

Ten tons of superphosphated manure per acre is enough for corn, especially on fields where other crops in the rotation are manured or where a good legume sod is turned under for corn. Lighter applications have proved profitable for winter grains. Manure used for such delicate feeders as wheat is most effective if applied early enough to get decay under way before the seed is planted. Plowed under before seeding, manure gives a greater increase in wheat yield than if used as a top-dressing during the winter; however, the clover seeded in wheat is benefited more by winter top-dressing.

A light coat of manure gives some winter protection on exposed areas; for example, on knolls or ridges in an alfalfa or clover field where the snow blows off.

Pastures with a fair stand of grass, poor new seedings, and old timothy fields respond to light top-dressings. Timothy fields are more likely to respond profitably if they have had a fair amount of superphosphate and lime when seeded down.

Results of light and heavy applications of manure on timothy, at Alfred, Allegany County, New York, illustrate how the suggestions made operate in practice (table 2).

The graph on the cover page shows that it pays to keep the rate of application under rather than more than 8 tons to an acre. In this 36-year experiment conducted at the Ohio Agricultural Experiment Station, manure was applied to wheat in a potato, wheat, and clover rotation. Two high-value crops in a short rotation may account for the relatively higher values of increase per ton of manure applied, as compared with similar experiments which prove the same point, but at a lower level of values per ton.

Use a Spreader

A spreader may be adjusted to make uniform light applications. Most farmers without a spreader could do a better job than they are now doing by hand. Manure should be put on in sheets, not chunks.

Add Superphosphate to Manure

From 1 to 2 pounds of superphosphate per cow per day in the stable and box stalls makes up for the naturally low phosphorus content of manure, saves nitrogen, and keeps down odors.

One hundred pounds of granular superphosphate absorbs about 30 pounds of liquid. Powdered superphosphate holds about twice as much liquid as does the granular type, but the stable deck is less slippery and less dusty when the granular type is used.

Hydrated lime speeds up the loss of ammonia nitrogen and should not be used in the stable. To save time and labor, ground limestone may be spread over the top of each load of manure, with no damaging effects.

Use Plenty of Bedding

Surplus cornstalks, chopped or shredded, make good bedding. The ordinary bedding materials vary greatly in their ability to absorb liquid. It takes only 25 pounds of shredded cornstalks, chopped straw, sawdust, or softwood shavings, 35 pounds of oat straw, but 45 pounds of wheat or rye straw to absorb 100 pounds of liquid.

Haul and Spread Manure Every Day of the Year if Possible

If it is impossible to spread manure every day, the farmer should make high and compact piles. To leach, water must pass through the manure; therefore, the piles should be covered to protect them from rain.

Handling manure only once saves time and labor. Generally, manure is in its safest place when it is on the field. Unless a sudden thaw causes rapid runoff on steep fields, leachings pass directly into the soil. The soil particles “hang on” to the leachings until used by plants, so there is less loss in daily spreading than when manure is piled. In a 40-year experiment conducted at the Ohio station, manure exposed in a barnyard pile from January to April has produced 13 per cent less total weight of crops than manure spread on the field in January.

For Cultivated Crops and Small Grains

If the manure is piled, the application should be made close to the planting and the manure either plowed down or thoroughly harrowed in immediately after spreading.

Top-Dress Some Pasture Every Year

Pasture is the cheapest livestock feed. It responds to manure and superphosphate. Pasture may be treated when there is no other place available.

A light coat of manure keeps cattle from overgrazing new seeded areas. Poultry manure may be used on steep rough pastures.

Scatter pasture droppings each fall.

Cover as much crop and pasture land as possible each year.

Do not expect manure to do the whole job.

Manure does not take the place of good crop rotations, lime on soils that need it, phosphorus fertilizers, legumes, and good tillage practices. Combined with these, maximum returns from manure are assured.