Alfalfa (Medicago Sativa. L) Yield and Quality influenced by Potassium and Magnesium Fertilization
2006
Aziz, Majhdi | Kharzmi, Kambiz | Abdollahi, Mosa
High producting alfalfa (Medicago Sativa. L ) uses large amounts of soil potassium(K) and magnesium(Mg). K fertilization increases alfalfa yield but the changes in yield as influenced by combined K and (or) Mg fertility level are not known. Our hypothesis is that K and Mg antagonism effects will influence yield and quality of alfalfa. The objective was to determine the impact of K and Mg fertilization on alfalfa yield and yield component during the initial 3 yr after establishment. Treatments were the factorial combination of four K levels (0, 100, 200 and 300 kg K2SO4. ha-1) and three Mg levels (0, 100 and 200 kg MgSO4 ha-1) arranged in a randomized complete block design with three replications. Application of K resulted in increased dry matter (DM) production. Total K removal in the herbage increased linearly with each rate of K and reached 1440 kg K ha-1 with the application of 300 kg K2SO4. ha-1 yr-1, compared with 900 kg K ha-1 without K fertilization. K fertilization also decreased plant tissue N concentration. Addition of Mg had a partially effect on DM production. Addition of K depressed plant tissue Mg, and plant Mg uptake. Addition of Mg decreased K uptake. Increment additions of K increased alfalfa grain yield, K concentration and uptake in 3d yr after establishment. Mg fertilization did not influence grain yield and Mg content in grains. At the end of the experiment, soil ammonium acetate extractable K (Ke) decreased considerably in check plot (127 mg.kg-1), but it increased with K rates.
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