Premium
Potassium Fertilization of Alfalfa Grown on a Soil High in Potassium 1
Author(s) -
Barbarick K. A.
Publication year - 1985
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1985.00021962007700030020x
Subject(s) - dry matter , loam , agronomy , potassium , fertilizer , chemistry , soil water , yield (engineering) , field experiment , potash , human fertilization , zoology , environmental science , biology , soil science , materials science , organic chemistry , metallurgy
Most Colorado soils contain adequate levels of plant‐available K. This study investigated the influence of up to 750 kg K ha −1 on four semidormant varieties of alfalfa ( Medicago sativa L.) grown on a soil high in K (Nunn clay loam—Aridic Argiustoll) over 4 years. Fertilizer K significantly increased dry matter yield for the first 2 years and significantly increased the total alfalfa yields for the entire duration of the study. The overall yield response, however, was not cost efficient based on current K fertilizer costs. Along with the yield increases, K fertilizer consistently decreased Na plant concentrations, Na uptake, and soil levels of Na. It is postulated that the additional K suppressed Na uptake which possibly resulted in greater N 2 fixation and dry matter production. A greenhouse study using four rates of K and Mg applied as K 2 SO 4 and MgSO 4 , respectively, showed that both materials equally reduced Na uptake and increased yields of the ‘Baker’ cv. Consequently, the yield response to applied K in the field was not a nutritional response to K but resulted from the suppression of Na uptake. This K‐Na interaction produced significant yield responses in the field and the greenhouse even though the Nunn soil (a fine, montmorillonitic, mesic Aridic Argiustoll) is a non‐sodic soil.