Results of an experiment at Rothamsted testing farmyard manure and N, P and K fertilizers on five arable crops II. Nutrients removed by crops

Abstract

1. The amounts of N, P and K recovered by five arable crops and by permanent grass from soil alone, and from fertilizer and farmyard manure (FYM) dressings were measured. All the crops responded well to P and K fertilizers and all except clover responded to N. Uptakes from soil alone are therefore the maximum amounts of each nutrient that each crop could remove when supplied with other fertilizer nutrients (the exchangeable Ca and Mg in the soil were adequate).2. Permanent grass (free from legumes) obtained about 114 lb. N/acre each year from soil and other natural sources; winter wheat obtained 1001b. N, kale and potatoes about 80 lb. N and spring barley only 57 lb. A 1 year ley of clover and grass fixed at least 1 cwt. N/aere/year. Permanent grass removed most P from soil (17 lb./acre a year), potatoes removed least (6 lb. of P) and other crops intermediate amounts. Most K was taken from soil by kale (70 lb. K/acre/year) and least (20 lb.) by potatoes. Annual variations in the amounts of nutrients recovered from soil by any one crop were much greater with K than with N or P.3. Most fertilizer N was recovered by kale and least by potatoes; with these crops two-thirds and one-third respectively of the light dressing was recovered, percentage recovery from the higher rate of N tested was less. Kale and the 1 year ley recovered nearly one-quarter of the P applied, permanent grass recovered little more than one-tenth. Clover-grass ley recovered most fertilizer K, apparently taking up four-fifths of that applied. Potatoes, kale and permanent grass all recovered more than half of the fertilizer K given, cereals were least efficient although both responded well to K dressings.4. Farmyard manure supplied large amounts of nutrients to all crops. Similar amounts of N, P and K appeared to be recovered from FYM whether or not NPK fertilizer was also used. A rough estimate was that crops like kale, potatoes and permanent grass, which received FYM each year, recovered about 30 lb. of N, 4 lb. of P and 75 lb. of K from a 10 tons/acre dressing.