Procurement of materials such as bituminous compound, polythene, fixing materials etc. may be done for rainguarding. Depending on the area to be covered, the rainguarding may be undertaken from April.
Spraying for the control of Abnormal leaf fall
The materials viz. Copper sulphate, lime, COC, spray oil etc. required for prophylactic spraying in May against abnormal leaf fall may be procured 30-50 kg of CuSO4 and lime or 8 kg COC and 40 L spray oil may be required per hectare. The spray equipment may be serviced well in advance.
Weeding should be carried out before the fertilizer application. Weeds are then kept aside for drying and dried weeds can be used for mulching the plant basin.
Land preparation for new planting and replanting can be continued during this period. Large trees of economic value should be removed first followed by felling and removal of smaller trees and slashing of undergrowth in the case of new planting. A light burn after felling and drying facilitates planting operations. Lining, terracing and pitting also may be undertaken during this period. Rubber may be planted either by adopting square (for level land) or rectangular (for level and near level lands) planting system. In undulating and hilly areas, contour lining should be undertaken and terraces should be cut along the contour to conserve moisture and prevent soil erosion. Instead of taking continuous terraces in the beginning, for economy, individual square platforms of size 1.25 m x 1.25 m can be constructed around each plant point and later on they can be joined together to form continuous terraces. Provision should be made for proper drainage.
The density recommended for proper growth and development of rubber is about 420-445 plants/ha. In the case of budded plants. It is preferable that the density should not exceed 500/ha.
Pitting and refilling
The standard size of the pit is 75 cm x 75 cm x 75 cm. In hard and stony soils, pits of size 90 cm x 90 cm x 90 cm can be taken. Filling should be done with top fertile soil. Well decomposed and powdered cow dung or compost at the rate of 12 kg and rock phosphate at the rate of 175 g per pit may be mixed with the top 30 cm soil in the pit.
Soil and water conservation
In sloppy areas, soil conservation measures may be undertaken at the time of land preparation itself to prevent soil erosion and to conserve water. Construction of stone pitched contour bunds (Edakkayyalas) and silt pits are the common conservation practices recommended other than contour terracing. Silt pits (trenches) of about 120 cm length , 45 cm width and 60 cm depth can be taken across the slope on the interspaces of rubber at the rate of about 250 pits per hectares.
Fertilizer recommendation to the individual fields based on soil and or leaf analysis will be more advantageous and economical and as far as possible it has to be followed. The facilities at the central soil and leaf testing laboratory attached to the Rubber Research Institute of India or the Regional laboratories can be utilized.
Immature rubber up to 4th year of planting
April – May is the planting season and for new plantings no fertilizer application is required during this time. For the initial four years, the discriminatory fertilizer recommendation based on the initial soil sample analysis if available can be followed. Otherwise the general fertilizer recommendation given below in table can be practiced. Two types of fertilizer mixtures either with magnesium or without magnesium is recommended. In Kanyakumari district of Tamilnadu, Trissur, Palakkad, Malappuram, Kozhikode, Kannur, Kasaragod, Wynad districts of Kerala, Karnataka, Goa and Maharashtra regions the magnesium status of the soil is high and here 12:12:6 mixture is recommended. For all other regions in the traditional belt of rubber cultivation, Mg containing 10:10:4:1.5 NPKMg mixture is recommended. For Northeastern region 12:12:6 mixture is recommended. Similarly in the initial two years fertilizer mixtures containing half the quantity of phosphorus in the water soluble form will be more useful for better root development and plant establishment.