The structure of the soil and soil characteristics that shall limit the walnut cultivation should be investigated in order to examine the suitableness of an area for walnut cultivation.

 

The walnut trees grow more strongly in uncongested, medium – thin textured or sandy soil, and the roots go deeper. The water-holding capacity of soils which are rich in argillaceous – sandy organic substances is higher. The infiltration speed of fine textured, argillaceous soils is slow. Ventilation in these soils is limited. Water is held more strongly and drained more slowly in argillaceous soils than sandy soils, due to little pores. This situation reduces the ventilation of the roots and O2 exchange. Rooting depth is superficial in argillaceous soils.

Because ventilation is slow and O2 is found lesser in deeper parts. Sandy soils are drained quickly and good, their water-holding capacity is low and are weak in respect of nutrition elements. In sandy – pebbly soils, there is very little water. Regular and frequent irrigation is made on these soils. Infiltration is coming down of water from the surface of the soil with the influence of gravity. The pores are full of air and water. Water fills the little pores, and air fills the bigger pores. If less than 10% of cell gaps are filled with O2; anoxia problem may occur in the roots. The root system of the walnut, as in the other perennial types, provides functions such as holding onto soil, absorption of water and nutrition elements, hormone synthesis location, exchange and storage of organic elements. In section -“soil requirements of walnut”, surrounding of the soil and the interactions of root and breeding rootstock shall be reviewed.

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