Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Agricultural Engineering


Soil nutrients need to be replenished from year to year. Nitrogen is a primary structural block in· proteins, chlorophyll, and many other compounds of plant and animal matter. One method of nutrient replenishment is to apply commercial fertilizer. This is especially important for pastures and grassland since very little organic matter is annually returned and mixed into the soil by cultural practices. Anhydrous ammonia, NH3, is one of the common nitrogen carrier fertilizers. Nitrogen fertilizers include anhydrous ammonia, which is handled as a liquid under pressure, liquid solutions, and nitrogen compounds in a granular state. Anhydrous ammonia injected beneath the soil surface is adsorbed by clay particles and organic matter, and it becomes readily available for use upon nitrification. Anhydrous ammonia contains the most nitrogen, 82 percent by weight, of all commercial fertilizers. Also, modern production methods by the Haber process have lowered the cost of anhydrous ammonia to be very economically competitive with other nitrogen fertilizers. The price of anhydrous ammonia in the Brookings, South Dakota, vicinity in October,1970, was 5 cents per lb. of actual nitrogen compared with 9 cents per lb. of nitrogen in ammonium nitrate, NH4No3, which contains 34 percent nitrogen by weight. Respective prices in May 1971, were 5 1/2 and 10 cents. Anhydrous ammonia is low in cost per unit of nitrogen. Less than 5 percent of the estimated 50 million acres of grassland in the north central and northeastern states are fertilized with nitrogen. Granular fertilizer may remain inactive in the soil until moisture dissolves it and then leaches it to the grass root zone. Nitrogen left on the soil surface is subject to erosion loss. Anhydrous ammonia is placed in the root zone initially during its application. Although anhydrous ammonia has been used extensively on tilled land, information is relatively scarce on its use on grassland. A brief summary is given in the Review of Literature. Research is needed to learn more about the feasibility of using anhydrous ammonia as an effective, economical method of grassland improvement. Other methods of grassland improvement in addition-to fertilization include renovation by tilling and reseeding, but this method damages the established vegetation. Legumes and grasses interseeded in furrows, from which the sod has been removed, is a recently developed practice. This also impairs some of the plants. Consequently, a knife inter seeder may be desirable to inter seed sod while anhydrous ammonia or a liquid starter fertilizer is applied. A versatile applicator with flexible, individual units that could be used for fertilizing and interseeding grassland as well as fertilizing tilled soil would be beneficial to farmers and ranchers.

Library of Congress Subject Headings

Fertilizer spreaders
Pastures -- Fertilizers



Number of Pages



South Dakota State University