what is the plant population per hectare of american cotton when seed rate is used 15-20 kg/hectare?
Answers
6. Preparation of land The time available for land preparation following the harvest of wheat is limited in the north zone. Pre-sowing irrigation is undertaken after the harvest of wheat. The land is worked upon with tractor-drawn implements, then levelled & planked before preparing ridges upon which sowing is done. In central and southern zone of India where cotton is a rainfed crop, deep ploughing recommended to destroy perennial weeds once in 4 years. The field is prepared by repeated harrowing with a blade harrow prior to the onset of pre-monsoon rains. Sowing is undertaken on ridges & furrows in drylands for moisture conservation & weed management.
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7. Method of sowing Cotton is sown using tractor or bullock drawn seed drill or by dibbling. Hand dibbling of seeds at recommended spacing is commonly practiced in rainfed areas particularly for hybrids. This system ensures proper plant stand, uniform geometry and also saves seeds. This is now main system of sowing of Bt. Hybrids. Cotton cultivation on ridges across the slopes conserves more water, reduces soil erosion and improves yield.
8. Irrigation Scheduling Depending upon the climate & crop-growing period, cotton needs 700-1,200 mm water to meet its maximum water requirement. The water requirement is low during first 60-70 days after sowing & highest during flowering & boll development. Cotton is commonly flood irrigated although irrigation by furrow or alternate furrow method is more effective and water saving. Drip irrigation is becoming popular particularly in the hybrids for central and southern zones. Cotton needs to be irrigated at 50-70% depletion of available soil moisture. On sandy loam soils of northern zone 3-5 irrigations are commonly given. On red sandy loam soils of Tamil Nadu with low water retention capacity, 4-13 light irrigations may be necessary.
9. Inter cultivation & weed control Inter-cultivation is done fairly regularly by either a blade harrow with a three tined hoe or a desi plough. In the crop sown by broadcasting, one or two hand hoeing’s are given to remove weeds, inter-cultivation not only checks the growth of weeds but also leads to better soil aeration and soil moisture conservation. Weeds compete with cotton crop for nutrients, light and moisture. Cotton is susceptible to weed competition from sowing to about 70 days when the canopy covers the inter-spaces. Cotton yields are reduced by 50 to 85% if weed growth is unchecked. Fluchloralin or pendimethalin @ 1 kg ai/ha. as pre-plant incorporation with one hand weeding and crosswise hoeing has been recommended for satisfactory weed control. Deep rooted perennial weeds are removed by summer ploughing. The thinning of the cotton crop is a special feature of the irrigated crop sown on ridges in Peninsular India and in parts of southern Gujarat. Thinning is desirable for
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maintaining the optimum population of plants to obtain a high yield. During thinning, the vigorous seedlings are retained and weak seedlings and off types are removed.
10. Fertilizer doses and method of application recommended for cotton crop in different zones Cultural Practices Northern cotton zone Central cotton zone Southern cotton zone Fertilizers N - 60 - 100 kg / ha. P and K dose as per soil test. No P need be applied if previous wheat received recommended P. 5.5 kg.Zn / ha. as ZnSo4 once in two cotton - wheat cycles N : P : K 40 - 20 - 20, 50 - 25 - 25, 80 - 40 - 40 for varieties 100 - 50 - 50, 160 - 80 - 80, 240 - 120 - 120, for hybrids N : P : K 40 - 20 - 20,60 - 30 - 30, 90 - 45 - 45 for varieties 100 - 50 - 50, 120 - 60 - 60, 150 - 60 - 60 for hybrids Method of fertilizer application i) Half N at thinning and remaining at first flowering; ii) Half N at sowing time in late sown crop; iii) Foliar application of N if needed; P to be drilled at sowing. N in three splits at sowing, squaring and peak flowering stages. ( P & K according to soil test). Application of 2 % urea or DAP at flowering and early boll development. N at squaring and peak flowering, P & K at sowing. In Karnataka entire NPK at planting ( rain fed cotton ), Half N and entire P & K at planting, remaining N at flowering (irrigated cotton ) N in 4 splits in irrigated hybrid cotton. Bio fertilizer Seed treatment with azotobacter is beneficial. Seed and soil treatment with Azospirillium in Tamil Nadu.
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