Studies on the Performance of Alfalfa Swards : IV. Effects of varieties, cutting frequencies and fertilizer levels on the yield and plant numbers

Abstract

Effects of varieties (Du Puits, Moapa, Rambler), cutting frequencies (3, 4, 5 cuts per year) and fertilizer levels (0, 50, 100 kg compound fertilizer <N-6, P2O5-11, K2O-11> /10a/year) on the yield and plant numbers per unit area of alfalfa swards were investigated on the alluval soil in Sapporo from 1967 to 1970. 2. Sources of variations that affected on the yield and plant numbers per unit area were varieties, cutting frequencies and interactions between the two. Fertilizer levels within a range of this experiment had no effects on the yield and plant numbers per unit area. 3. In totals for four years period, the yields of Rambler were reduced accordind as increased cutting frequencies. The yields of three-cut and four-cut treatments of Du Puits, and also Moapa, were similar, and higher than those of five-cut treatments. The rate of yield decline from four-cut treatments to five-cut treatments of Moapa was much smaller than that of Du Puits. The yields for four years period showed the ranking order: Du Puits > Moapa = Rambler under three-cut treatment, Du Puits > Moapa > Rambler under four-cut treatments, Du Puits = Moapa > Rambler under five-cut treatments. 4. Plant numbers of Rambler per unit area at the first harvest in the fourth year were reduced according as increased cutting frequencies. The three-cut and four-cut treatments of Du Puits, and also Moapa, had similar plant numbers per unit area, and more plant numbers than five-cut treatments. The rate of decline in plant numbers of Moapa from four-cut treatments to five-cut treatments was smaller than that of Du Puits. Plant numbers per unit area at the first harvest in the fourth year showed the ranking order: Du Puits = Nloapa > Rambler under three-cut and four-cut treatments, Moapa > Du Puits > Rambler under five-cut treatments. 5. There existed correlations between annual yields and plant numbers per unit area at the final harvest of that year, total yields for four years period and plant numbers per unit area at the first harvest in the fourth year. These relationships, however, did not lead to the conclusion that plant numbers per unit area were responsible for sward yields.