Saturday, 15 July 2006
153-21

Effect of Tillage, Irrigation and Nutrient Levels on Seedling Emergence, Yield and Water Use Efficiency of Rabi Sunflower (Helianthus annus L.) in Rice Based Cropping System.

Singarao Meduri and Praveen Kumar. Acharya N.G. Ranga Agricultural Univ, Rajendranagar, Hyderabad, 500030, India

Growing of upland crops like oilseeds and pulses after rainy season puddled rice instead of second crop rice is advantageous because of low water requirement, better remuneration,improved soil health,balanced food production etc.However,the yield of such upland crops grown after puddled rice is low as compared to the normal yield because of unfavourable soil environment.In southern part of India including Andhra Pradesh, sunflower crop is grown during post rainy season in rice based cropping system. Sunflower (Helianthus annuus.L) crop due to its short duration, low photo and thermo insensitivity and wide adoptability to different soil types fits well in rice based cropping system. Puddling for rice cultivation during rainy season destroys soil structure, increases bulk density and reduces macro porosity making soil impervious, massive and compact after drying. These soil conditions pose limitations for subsequently grown upland crops, which prefer fractured structure. Massive and compact (less porous) rice fallow soils adversely affect air and nutrient movement, particularly phosphorus and potassium in the soils, besides low water retention capacity, poor plant stand and restricted root growth. Effective and low cost tillage practices to eliminate drudging and to ensure proper seedbed preparation are urgently needed for post rainy season upland crops grown in rice fallows, besides efficient utilization of water and nutrients. Keeping these points in view a field experiment was conducted for two years (2001-02 and 2002-03) in sandy clay loam soil at the Agricultural College farm of Acharya N.G Ranga Agricultural University to find out the optimum tillage, irrigation and nutrient requirements of sunflower in rice fallows. Three tillage practices viz.,T1 – country plough twice+ cultivator twice ( both bullock drawn), T2 – country plough twice + power tiller rotavator twice and T3 – Disc plough once + rotavator once ( both tractor drawn) were adopted as main plot treatments. Three irrigation levels as subplot treratments viz., IW/CPE of 0.6 (I1), 0.8 (I2) and 1.0 (I3) and three nutrient levels viz.,75 (F1), 100 (F2) and 125 (F3) percent recommended dose of NPK were tried in sub-sub plots in double split plot design with three replications. Sunflower (APSH-11) was taken as a test crop. Tillage was assessed in terms of mean weight diameter, bulk density, porosity, penetration resistance, hydraulic conductivity and infiltration rate of soil.These tillage induced changes in soil physical properties along with different irrigation levels and nutrient levels were studied on rabi sunflower. Favorable soil physical environment (deep and fine tilth) expressed in terms of low Mean Weight Diameter (MWD) of clods (24-27 mm), low BD, low penetration resistance, high porosity, high infiltration rate and hydraulic conductivity was obtained when tillage was done with tractor drawn implements. Better seed soil contact facilitated by the secondary tillage done with rotavator (tractor or power tiller drawn) ensured high seedling emergence ( 73-76 %).A step down regression indicates seedling emergence mainly depends on dry clod mean weight diameter of seedbed. Tillage with tractor drawn implements, irrigations given at IW/CPE = 1.0 and application of 125 percent RDF resulted in better crop growth (plant height, LAI, dry matter production) and seed yield. Interaction studies on seed yield revealed that, no significant difference was observed between T3 I1 and T2 I3; and betweenT3 F1 and T1 F3 which indicate that through adoption of deep tillage a saving of 3-4 irrigations and 40 kg N, 45 kg P2 O5 and 15kg K2 O would be attained. Similarly, no significant difference was observed between I3 F1 and I2 F3 which indicate by giving 2-3 irrigations we can reduce the application of 40kg N,45kg P2 O5 and 15kg K2 O. Water Use Efficiency was higher with deep tillage (3.80 kg ha-1 mm-1), irrigations at IW/CPE =0.6(3.61 kg ha-1 mm-1) and application of 125 percent recommended dose of fertilizers (3.46 kg ha-1 mm-1).


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