Correct planting of high quality seed of the right cultivar in a wellprepared seed bed consisting of friable moist soil, forms the basis of a good crop. By correct planting we mean:
* the right planting date;
* planting at an optimum density;
* planting at an even and correct depth, which can be achieved only by a skilled tractor driver who has been well instructed.
It is very important to take adequate account of the actual conditions at the planting site and to make an accurate assessment of the consequences of certain choices. This edition of Professional Potato Growing discusses the management decisions, the necessary checks and actual operations involved during planting.
The period between planting and emergence is the most delicate stage of a potato crop. As optimum sprout development is highly infl uenced by the quality of the seed, age and sprouting stage, as well as by the proper soil conditions, especially temperature and moisture at planting time, the seed bed must meet high requirements.
In a good seed bed, the air, moisture and soil ratio is optimal. The environment then created will be conducive to a uniform emergence and undisturbed growth of the potato crop. The seed bed should be level, free from clods and have a fairly fine crumbled, loose soil layer with a depth of 8 to 10 cm, which is sufficiently firm and moist and permits the building of a well-formed ridge. A fine soil structure also helps to avoid rapid drying out of the ridge while, on the other hand, excessive soil tillage may lead to soil compaction and an unwanted reduction in the amount of soil water available to the crop. Potatoes are shallow-rooted, and both roots and tuber growth are extremely sensitive to soil compaction. For these reasons, the number of tillage operations must be minimized.
Soil moisture markedly infl uences germination of theseed. If the soil is too dry, emergence is delayed andthe number of stems is reduced. With normal soilmoisture, emergence occurs rapidly and, soon after planting, the sprouts produce rootswhich take up water from the soil. Insaturated soil, the seed decays dueto lack of oxygen. For this reason,heavy irrigation soon after plantingis detrimental and pre-planting irrigationshould be considered fi rst. Thus,seed potatoes should be surroundedby moist soil or at least be plantedin moist soil. The seed should becovered with a layer of soil suffi cientto prevent the soil around the tuberfrom drying out too soon, while thesubsoil should allow unhindered rootdevelopment to guarantee an adequatemoisture supply throughoutthe growing season.