Fertilizer placement for horticultural crops

Extract

In field experiments on vegetable crops dressings of appropriate fertilizers were placed 2 in. to the side of the seed and 2–3 in. below the soil surface, and compared with the same amounts of fertilizer broadcast and worked into the surface soil. The work was carried out on ordinary arable land carrying rotations which included vegetables.

Placing fertilizer gave higher yields of cabbage, lettuce, beetroot, onions, broad beans, runner beans and maize, than broadcasting. Fertilizer, however applied, had no regular effect on the yield of french beans.

Both placed and broadcast fertilizer were tested at two rates of dressing. On average of all experiments on each crop, placing fertilizer at the low rate gave higher yields than broadcasting at the high rate. Broadcast fertilizer had little effect on yields of runner beans and broad beans, while placed dressings gave marked increases.

In two-thirds of all individual experiments placing gave higher yields than broadcasting, and in one-third of the experiments placement was significantly better than broadcasting. There were no instances of significantly higher yields from broadcasting as compared with placing.

Placing fertilizer made most of the crops grow more rapidly in the early stages than broadcasting, this improvement being often reflected in earlier maturity. For cabbage, lettuce and runner beans the relative gains from placing, as compared with broadcasting fertilizer, were much higher at the first than at the second harvest.

By drilling fertilizer beside the seed of vegetable crops grown on ordinary soils, it is possible to economize in the dressings needed. In addition, some crops having placed fertilizer may be ready for market earlier. These advantages may be very profitable where high-value crops are grown and will justify the purchase of special placement drills.

A small series of field experiments on established Brussels sprouts and autumn-planted cabbages compared mid-season top-dressings of nitrogen fertilizer broadcast by hand over the whole soil surface, with dressings placed at one point beneath the surface and near to the plants. The dressings used had practically no effect on yields of Brussels sprouts. Top-dressings broadcast in spring increased yields appreciably in two experiments on cabbage, and at both centres placing gave lower yields than broadcasting.