Agriculture for Engineers 4 (3+1)

Lesson 47. Management of Orchard

Management of Orchard

47.1 Orchard Management

Careful management of orchard is essential for successful fruit growing. Main cultural practices include those for better soil management, nutrition, training and pruning, irrigation and weeding.

47.1.1 Soil Management Practices

Objectives of soil management practices are maintenance of physical condition of soil, efficient weed control, conservation of moisture level and checking of soil erosion. Various methods of soil management can be adopted to achieve these goals.

 i. No cultivation: This practice is followed in orchards of various countries including USA and Australia. Orchards believe that beneficial effects of soil cultivation are confined to top layer of 10-15 cm, whereas trees have much deeper root systems. Moreover, cost of orchard maintenance can be reduced to considerable extent by this method.

ii. Clean culture: Interspaces of orchards are kept clean by frequent ploughing. This is adopted extensively in India. Clean culture has advantage of no competition for water and nutrients by weeds with main crops but has a number of disadvantages. Frequent cultivation results in soil erosion, creation of hardpan in soil, depletion of humus and nitrogen levels and injury to feeding roots of crops.

iii. Cover cropping: Growing of cover crops or green manure crops after removing weeds in orchard has many advantages, important ones being checking soil erosion and enrichment of soil. Green manure crops like Sunnhemp, Cowpea, Daincha or any legume are sown in interspaces at onset of monsoon and incorporated into soil towards end of season for better results. Permanent cover crops are also graown in certain orchards with better results. Leguminous creepers like Calapagonium muconoides, Centrosema pubescens and Peuraria phaseoloides are preferred for this purpose. These plants dry up during summer to save moisture and start growing again in rainy season to from a mat in orchard, preventing weed growth and soil erosion.

iv. Sod culture and sod much: Maintaining a permanent cover of grass in interspaces is referred to as sod culture. This practice helps in reducing soil erosion especially in sloppy areas but compete with crops for moisture and nutrients, which make additional manuring and irrigation essential in orchards. If the grass is cut frequently and spread on ground, the system is called as sod mulch.

v. Mulching:  Mulching is a very important practice with a number of plus points. This helps in preventing soil erosion, reducing weed growth in turn cutting down cost of cultivation and adding organic matter to soil in many cases. Suitable materials such as straw, dried leaves, saw dust, coir dust, special types of paper and polythene sheets can be used for mulching.

vi. Intercropping: During initial years of orcharding, where fruit trees are in juvenile stage, there will be no returns from orchards. Intercropping is one of the best methods to tackle this problem. Growing intercrops not only fetches income to grower but also helps in soil management by reducing weed growth, checking erosion and enriching soil. Selection of crops for intercropping should be based on suitability and marketability. Fast growing and early fruiting crops like papaya, pineapple, banana, guava, vegetables such as brinjal, tomato, chillies and spices like ginger and turmeric can be selected based on other factors.

47.1.2 Nutritional Management                                 

As in any other crops, growth, development and productivity of fruit plants are also highly influenced by nutrient supply. Nutrient management is a very important aspect in orcharding. Plants require supply of sixteen elements of which carbon, hydrogen and oxygen are obtained from atmosphere and need not be applied. Nitrogen, phosphorus and potassium are major / primary elements required by plants in large quantities. Secondary nutrients include calcium, magnesium and sulphur used in considerable quantities for normal growth of plants. Minor or micronutrient elements comprise of iron, zinc, manganese, copper, boron, molybdenum and chlorine which are essential for normal growth and development, but in very small quantities. Elements such as sodium, aluminium, silicon and cobalt are required in traces for some fruit species. Specific functions are performed by various nutrient elements in all metabolic activities and growth, development, productivity and quality of plants and their produces. Lack of availability in sufficient quantities of nutrients causes deficiency symptoms expressed in different ways depending on specific roles played by the elements. On the other hand, supply of nutrients in excess results in toxicity symptoms, which may affect growth and development and may lead to mortality depending on intensity.

Nutritional requirement of a crop should be assessed before going for fertilizer and manurial application. Nutrient status of soils can be determined by soil analysis. Whole plant and plant part analysis may be useful to assess nutrient status of plants. Leaves being the main site of metabolism in plants, analysis of leaves is the most reliable diagnostic method n almost all plant species. Analysis of leaves at correct stage of development indicates nutrient status of whole plant based on which nutritional requirements and deficiency symptoms can be assessed. Diagnostic leaf to be used for analysis has already been standardized for different fruit species. Details of index leaves / tissues for important tropical and subtropical fruits are as follows:

Avocado	Fifty leaves from 5-7 months old non-fruiting terminal shoots.
Banana	Petiole of third open leaf from apex at four months after planting.
Ber	Recently matured leaves from middle part of secondary or tertiary shoots with a sample size of 40.
Citrus	Thirty leaves with petiole from new flush.
Custard apple	Fifth leaf from apex at two months after new growth with sample size of 30 numbers.
Fig	Twenty five fully expanded leaves from current shoots.
Grape	Petioles at fifth leaf position for forecasting yield and petioles opposite to bloom for quality.
Guava	Recently matured leaves (25) from third pairs on shoots.
Mango	4-7 months old leaves along with petiole from middle part of shoots.
Papaya	Sixth petiole from apex with a sample size of 20 numbers.
Pineapple	White basal portion of fourth leaf from apex.
Sapota	Tenth leaf from shoot apex with a sample size of 30.

 Organic and inorganic manures can be used as sources of nutrient elements for fruit crops. Continuous application of inorganic fertilizers results in soil destruction, which should be avoided as far as possible. Organic manures help in improvement of soil tilth, aeration, water holding capacity and microbial activities. Commonly available organic manures include farmyard manure, compost, vermicompost, leaf mould, oil cakes, fishmeal and meat meal. Biofertilizers help in improving soil characters and plant growth and fruit quality through enhancing hormonal activities. Commonly used growth promoting organisms of biofertilizers include Rhizobium species, Azospirillum, Pseudomonas and VAM (Vesicular-arbuscular mycorrhizae). Integrated nutrient management incorporating inorganic and organic sources of nutrients, biofertilizers and other practices, which will help to maintain soil health and environment is an ideal approach in orchard management.

 47.1.3 Irrigation

Requirement of water by plants differ according to climatic conditions, type of crop, type of soil, cultivation and management practices. Plant species vary in their capabilities to utilize available water or to withstand water stress. Quantity of water to be applied and frequency of irrigation should be standardized for a species under specific agro climatic conditions. Irrigation is a very important operation accounting a considerable portion of cost of production. Economic and judicious use of water for betterment of crop should be followed for successful fruit culture. Availability of water source is a primary criterion for selecting site for orchard. During establishment stage, watering is inevitable for all fruit crops. Afterwards, requirement of irrigation depends on crop nature and critical stages. For example, grape requires high moisture during flowering and berry development but needs a little stress during ripening. Banana and papaya require high moisture during growth and fruit development. Citrus needs stress to induce flowering but blooming and fruit development demand ample moisture.

Different methods of watering are available, such as surface irrigation, sub irrigation and spray / sprinkling. Where water availability is rich, surface irrigation methods can be adopted. Basin and furrow systems come under this category apart from flooding. Basin method is widely practiced in orchards all over the world, where in shallow basins are taken surrounding plant bases and water is directed towards this either by channels or houses. Furrow system is one of the best methods of irrigation in orchards. Depth, length and width of furrows depend on nature of soil and spread of root system of crops. In general, depth of furrows varies from 10 to 25 cm. In sub irrigation system, water is applied below soil surface and here, water quantity required is very high and is feasible only in soil with specific strata of an imperious lower layer, open, porous intermediate layer and a finely textured top layer with capillary action. Spray systems of irrigation indicate application of water to soil surface in the form of sprays. Overhead or sprinkler method is expensive in the installation stage but uses less quantity of water and recurring expense is also less. Since water is applied from overhead, foliage of trees also gets washed with water simulating situation of natural rains. Modified method of sprinkling system is called as 'slop' irrigation in which water is poured to drench surface soil in root zone. Installation charges are more but loss of water through evaporation, seepage and runoff is relatively negligible. Drip irrigation is a modified version of slop system. Water is directly applied to root zone through conducting pipelines inside soil. Initial cost is very high but has the advantages of checking weed growth in orchard and increasing fruit yield. Both slop and drip systems are grouped under sub surface irrigation methods.

47.1.4 Training and Pruning

Training and pruning are essential operations in successful orcharding. Training is tying, fastening, staking or supporting a plant over a trellis or pergola in a certain fashion or pruning some parts for giving plants a definite framework. Pruning is scientific removal of buds, shoots or roots to produce more and superior quality of fruits. Training methods are adopted mainly in initial years whereas; pruning is to be performed annually to regulate fruit but formation.

 47.1.5 Weeding

Excessive weed growth in orchards affects growth and development of main crops. Weed growth should be controlled for better results. In clean cultivation, weeds are not allowed to grow through frequent cultivation of soil. In sod culture, controlled and selected grasses are grown in interspaces of orchards. Weeding is a routine orchard operation accounting a considerable portion of cost of production. Manual weeding is costly and availability of labour may be a problem. Use of herbicides is now being adopted for effective weed control in orchards throughout world. Herbicides can be grouped as contact chemicals, growth regulators and soil sterilants based on nature of action. Contact herbicides kill weeds soon after application and are more effective in annual weeds. Selective and non-selective herbicides are available in this category. Simazine, Diuron, EPTC, Nitrofen etc. are commonly used selective chemicals. Oil emulsions of DNBP and Pentachlorophenol are used as broad spectrum non-selective herbicides in orchards. Growth regulators such as 2,4-dichlorophenoxy acetic acid (2,4-D), 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) and methyl chlorophenoxy acetic acid (MCPA) are used as effective herbicides at higher concentrations of more than 1000 ppm. Soil sterilants are herbicides used for sterilizing soil to prevent growth of weeds. According to the duration of action these may be non-residual, temporary (effective for a few months) or permanent sterilants (effective for one or two years). Based on stage of application, herbicides may be pre-emergent or post emergent ones, former types mainly being used at time of land preparation and latter types being used frequently in orchards to control weed growth, which in turn reduce cost of cultivation and increase yield per unit area.

Application of herbicides in orchards is being widely practiced at present owing to beneficial effects associated with this operation. For different fruit crops, for specific growing conditions, type of herbicides, dosage and method of application have been standardized.