Prof R D Gupta
Soil is one of the most important natural resources of any country. It is the basic pillar for production of food crops and fruits. The main objective of writing of this article is to discuss soil requirements of some of the fruit trees that can be looked into by the prospective fruit grower himself before any orchard is laid out. It is not really the surface soil that should concern the prospective fruit grower so much so the sub-soil lying deep below the surface soil should also be examined. It is not necessary that a soil suitable for ordinary farm crops should also be suitable for fruit trees because roots of fruit trees go very deep. If the subsoil condition is not favourable, then the trees may grow nicely for a short time but will begin to decline as soon as the roots reach undesirable sub-soil.
Defective sub-soil: Condition of sub- soil should always be examined to a depth of at least 2 metres and preferably to 2.5 metres. If the examination shows the existence of a layer of gravel, Kanker or even coarse sand or a clayey plastic sub- soil or a hard pan, the land should be considered unsuitable for fruit orchards. A layer of gravel or even coarse sand is harmful because of lack of fertility and lack of water holding capacity. It does not permit the proper development of root system. Clayey soils on the other hand. Do not allow the irrigation or rain water to percolate water ultimately produces a water logged condition, which is extremely injurious for healthy growth of roots. Trees with constantly ‘wet feet’ turn yellow and eventually die.
Water logged soil and shallow water-table: A swampy or water logged soil should never be selected for fruit garden as in the absence of proper aeration in such soil roots cannot develop. Watertable must not be nearer than 2 metres or preferably 2.5-3.0 metres from surface of the soil. Where water-table is near, the fruit trees begin to become yellow and die after a few years when the roots reach at water table. A soil that becomes waterlogged even for few weeks in the year should not be selected unless some arrangements for artificial drainage exist.
Effect of salinity: Citrus is most sensitive of salinity and it is one of the most important causes of citrus decline in Punjab, Haryana and Jammu region of J & K state. A salinity limit of 0.5 to 0.8 m mhos has been found suitable for its successful growth. On the contrary, guava is more tolerant to salinity and a critical salinity level of 7.5 m mhos has been proposed. ECe (electrical conductivity of saturated paste extracts) of more than 1.4 m mhos has been considered harmful to the mango tree which has resulted in the decline of mango in Punjab and Haryana as well as Jammu region of J&K. In fruit crops, reclamation of salt affected soils by leaching is not practicable. Hence, their salt tolerant rootstocks and varieties can be successfully cultivated on these soils. Guava, pomegranate and fig are moderately tolerant whereas date and ber are highly salt tolerant and thus, can be cultivated on saline soils.
Type of rootstocks: Suitability of soil for any particular fruit also depends on the kind of rootstock used for grafting or budding. For instance, apricots can be budded on peach, plum and apricot stocks. Peach stock requires light warm sandy loam soil and will not flourish in moist heavy soil. But plum stock can grow very nicely in heavy moist soil. Similarly certain other rootstocks can withstand adverse soil climatic conditions. By budding grapes on Salt-creek and Dogridge rootstocks, can be grown safely in saline conditions. Likewise Rangpur lime and Citrus baxifolia rootstocks of citrus can also tolerate saline conditions upto some level. What type of soil is required for different types of fruit trees are the questions that is frequently asked by the prospective fruit growers. There is no doubt that some fruit trees are more exacting in their soil requirements that others as will be clear from the table given below. But can be safely said that any well drained soil that is neither too heavy nor too light and which is suitable for ordinary farm crops ought to successfully grow almost any kind of fruit tree provided it is under-land with a suitable sub-soil as already discussed. The optimum requirements of soils for different kinds of fruits are given below:
- Mandarin: Rich light loam soil of good depth is the best suited. Never select soils with gravely or clayey sub soil.
- Sweet Lime: It can be grown on a variety of soils and is rather tolerant to defective soil conditions. All the same, it does best on deep loam soils which are well drained.
- Sweet Orange (Mosambi): Mosambi can be grown on a wide range of soil from heavy clay to very light sandy. The tree is particularly sensitive high to concentration of salt and cannot stand water logged conditions for any length of time. Heavy soils if well drained may produce good crops. However, the ideal soil for Mosambi is medium or light loam with a slightly heavier sub- soil.
- Sweet Orange (Malta): Sandy loam to loam and well-drained soil, with the sub-soil free from any layer of gravel or hard pan is found to be the best. Avoid water logged soil conditions.
- Kagzi lime: It can be grown on a wide range of soils. A loamy soil of uniform texture upto a depth of 2.5 m, having good fertility, is considered the ideal one for its cultivation. Heavy soils, with well drained conditions yield good crops.
- Mango: It can be planted on any soil except alkaline water logged ones though a light sandy loam is better. Too heavy soils should be avoided.
- Litchi: It is not fastidious in its soil. It makes best growth in deep loam soil under slightly acidic conditions; culture of my corrhizal fungi should be applied to the soil. These fungi form nodules on the roots of litchi trees and the fungus lives together to the benefit of each other. If the corrhizal culture is not available then the addition of some soil from old litchi orchard will serve the purpose.
(The author is Ex-Associate Dean cum
Chief Scientist KVK, SKAUST-J).
