Manuring and spacing experiments on vegetables

摘要

Abstract The responses of lettuce, leeks, beetroot, carrots, pole beans, and savoy cabbage to five levels of sulphate of ammonia (N), serpentine superphosphate (P), sulphate of potash (K), and of spacing in the row (Sp) were successfully determined annually for 3 years on Levin silt loam (a yellow–brown loam) using 3 multifactor rotatable central composite designs of only 30 plots each. The results are expressed as the treatment levels which gave maximum gross profit as well as maximum salable yield, because maximum gross profit is the only single parameter which will integrate all the variables of treatment rate, yields in several size and quality grades, the value of each grade under different market supply conditions, and treatment costs. The levels for maximum profit in cwt fertiliser per acre and spacing in inches were: lettuce, N–71/2, P–27, K–4, and Sp in 12 in. rows–12; leeks, N–11, P–15, K–2, and Sp in 12 in. rows–8; beetroot, N–10, P–28, K–41/2 and Sp in 12 in. rows–51/4; carrots, N–0, P–30. K–7...