Topdressing


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Topdressing

 

the addition of fertilizers to crops during the growing season in order to improve plant nutrition and boost yields. Fertilizer is often applied to the soil, so that the nutrients are taken up by the roots. The plants may also be sprayed with solutions of fertilizers, and the nutrients penetrate the plants through the leaves and stems.

Topdressing was introduced by the German scientist P. Wagner in the late 19th century. In Russia, the first experiments with topdressing, using potassium nitrate, were carried out on oat shoots at the Derebchin experimental field (Ukraine) in the late 19th century. Despite the beneficial results—a yield increase of about 6 centners per hectare (ha)— the method was not widely adopted. It was not until 1935 that topdressing with mineral and organic fertilizers was used over large areas in the USSR.

The following techniques of topdressing are common. (1) Dry fertilizer is scattered by fertilizer distributors, by fertilizer spreaders, or from an airplane (winter crops, rice). Sometimes the fertilizer is applied manually. (2) Dry fertilizer is scattered and worked into the soil with harrows, cultivators, or other implements. (3) Water and fertilizer solutions are applied with waterers or from overhead sprinklers.

The effectiveness of topdressing depends on the weather and on the properties of the fertilizers— their solubility and the extent to which they migrate in the soil. Mineral fertilizers that are quickly soluble in water are most often used for topdressing. These include nitrogen fertilizers, including ammonium nitrate, urea, an aqueous solution of ammonia, and sodium nitrate (for sugar beets); all potassium fertilizers; and superphosphate. Local fertilizers (ash, liquid manure, poultry manure, rotted manure) and microfertilizers are also used.

Early spring topdressing of winter crops is very important. It is often carried out on frozen soil. Winter crops consume the most nutrients from initial spring growth to ear formation. At this time there is usually an inadequate supply of nutrients in the soil. The fertilizers added before sowing are absorbed by the soil, washed out by rain, and used by plants and microorganisms, and the nitrification process is still surpressed by the low temperature and high moisture content. The maximum increases in yield are obtained by using a complete fertilizer containing N, P2 O5, and K2O as topdressing. In regions with adequate moisture, nitrogen fertilizers should be applied twice— in early spring and before the stem extension stage. The average amount of fertilizers used as topdressing for winter crops is about 60 kg/ha of NPK, which produces an average increase in yield of 3-5 centners per ha. Row crops that should be topdressed during irrigation include cotton, sugar beets, and rice. In the Soviet Union, about 40 million ha have been topdressed every year since 1965. Top dressing is widely used in France, Italy, other European countries, the United States, and Canada.

N. S. AVDONIN

References in periodicals archive ?
Topdressing Spreading a thin layer of soil mix over a turf area and working it into the turf to stimulate thatch decomposition and to smooth the surface.
For treatments N270 and SN270, 65-86% of total seasonal [N.sub.2]O emission took place within I l days after the second topdressing of N fertiliser at panicle initiation.
Although the covering with topdressing sand may have had a negative effect on Kentucky bluegrass establishment, delayed sowing of red fescue and perennial ryegrass clearly had an increasing effect on the percentage of Kentucky bluegrass and in most cases a decreasing effect on the percentage of red fescue and particularly perennial ryegrass when measured after nine or twelve months (Table 2, Fig.
Once the sprigs start to grow, a light topdressing of soil encourages the stolons to spread.
Sand topdressing amended with Ringer Compost Plus, Ringer Green Restore, and Sustane as well as selected composts prepared from turkey litter and sewage sludge and non-composted blends of plant and animal meals also were reported to suppress dollar spot (Nelson and Craft, 1991b; Nelson and Craft, 1992).
At 30 DAS, topdressing fertilization was also performed on-line with castor bean cake, characterized by [Ca.sup.2+]: 12.95; [Mg.sup.2+]: 6.55; [K.sup.+]: 8.5; and P: 2.42[cmol.sub.c] [dm.sup.-3]; and N: 5.81%, (dose: 1.5Mg [ha.sup.-1]).
(2008) reported that the number of leaves per plant was influenced by the N applied as topdressing, following plant growth with production of leaves until the plant reached its maximum growth.
The use of alkaline irrigation water or topdressing materials should also be avoided.
Thirty days after transplanting, another 25 kg/ha of urea-N was applied as topdressing to all the plots, and thus, urea-N was applied at 50 kg/ha, which was 50% of recommended field rates for the crop.
The present management methods for high tillering creeping bentgrass cultivars grown on putting greens include mowing to less than 3-mm height and fertilizing at lower annual nitrogen rates; light, frequent topdressing; and core aeration six to eight times a year (E.K.
Topdressing fertilizations were performed at 25 days after planting (DAP), using 20 kg [ha.sup.-1] of nitrogen as urea and 30 kg [ha.sup.-1] of potassium as potassium chloride; at 45 DAP, a top-dressing fertilization was performed using 20 kg [ha.sup.-1] of nitrogen as urea, according to the recommendations for the crop in the state of Pernambuco (Cavalcanti, 2008).
The dose of N was divided into three equal parts and applied at planting, at 25 and 40 days after planting (DAP), the P was applied only as basal dose, while the dose of K was divided into two equal parts, half at planting and the other half as topdressing at 25DAP