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G.V. VENKATARAVANA NAYAKA* AND G. SOMANAGOUDA
Department of Agronomy, ARS, Annigeri, Karnataka, India
A field experiment was conducted at Agriculture Research Station, Annigeri, UAS, Dharwad during kharif and rabi seasons of 2014-15 under rainfed condition. The experiment was laid out in a split-split plot design with 18 treatment combinations replicated thrice. Main plots consisted of three treatments, greengram for green manuring and greengram as a dual purpose both grown during kharif and one fallow. Succeeding safflower was sown during rabi season with two spacing’s of 45 cm × 20 cm and 60 cm × 30 cm as sub plots and three nitrogen levels 20, 30 and 40 kg N ha-1 as sub sub plots. The available N in soil showed positive improvement over initial status after the harvest of safflower. Among the green manure treatments, GM1 recorded highest soil N content in 0-15 cm and 15-30 cm (245.15 kg ha-1 and 249.27 kg ha-1, respectively), as compared to rest of the green manure treatments GM2 (233.24 kg ha-1 and 237.43 kg ha-1, respectively) and GM1 (224.04 kg ha-1 and 228.01 kg ha-1, respectively), at the time of safflower harvest.
Green Manuring, Dual Purpose, Nutrients, Uptake, Greengram and Safflower
Since safflower is more drought and salt tolerant than some other oilseed crops, it is especially suited for dryland and salty areas where other oilseed crops are difficult to grow (Weiss, 2000). Also, low production costs and low water and nutrient needs appeal to farmers as an alternative to other crops. However, safflower yields are generally lower than the yield of other oilseed crops (Mundel et al., 2004). Safflower is predominantly grown in black soils (medium and deep black soils) as a rainfed oilseed crop in the Deccan plateau region of India during rabi season (post rainy season) (Vishwanath et al., 2006). In India, the crop has traditionally been grown in the ‘rabi’ or winter dry season in mixtures (inter-crop) with other ‘rabi’ crops, such as wheat, chickpea and sorghum. As a sole crop (yearly rotation) it is also rotated with wheat, chickpea, cotton and sorghum. Being deep rooted with spiny leaves it is considered a drought tolerant crop, and it responds well to residual moisture, nutrients and management practices in dryland conditions. After emergence, the crop maintains a rosette form few weeks before rapid elongation. The florets are mostly self-pollinating but seed set can be increased by the presence of bees or other insects (Bahman et al., 2013).
The field study was conducted during kharif and rabi seasons of 2014-15 under rainfed conditions at the Agricultural Research Station, Annigeri, Dharwad. The experiment was laid out in a split-split plot design and replicated thrice. Main plot consist of three treatments, greengram as a green manuring (GM1) and greengram as a dual purpose (GM2) grown during kharif and one fallow (GM3). Succeeding safflower was sown during rabi season. Two sub treatments spacings (S1: 45 cm × 20 cm and S2: 60 cm × 30 cm) and nitrogen levels (N1: 20, N2:30 and N3: 40 kg N ha-1) were applied to succeeding safflower.
The greengram crop was sown with the onset of monsoon (12th June 2014) at row spacing of 30 cm with seed rate of 12.5 kg ha-1. Greengram crop was given a common dose of fertilizer of 25:50:25 kg N: P2O5: K2O ha-1 at the time of sowing. Green manure GM1 i.e. incorporation of greengram as a green manure at full bloom stage (45-50 DAS) in field was done on 1st August 2014. And GM2 greengram as a dual purpose i.e. incorporation after picking of pods was carried out on (20-08-2014).
In dual purpose greengram treatment was noticed nitrogen, phosphorous and potassium uptake (43.67, 9.27 and 20.02 kg ha-1, respectively) (Fig. 1). Among the green manure treatments GM1 recorded significantly the higher nitrogen, phosphorous and potassium uptake by safflower (96.75, 21.01 and 47.68 kg ha-1, respectively). While the lowest nitrogen uptake, phosphorous uptake and potassium uptake was recorded in crop raised on previous fallow land (87.72 kg ha-1, 18.31 kg ha-1 and 42.48 kg ha-1, respectively), and the GM2 was on par with GM1 (93.55 kg ha-1, 19.40 kg ha-1 and 45.84 kg ha-1, respectively), which was 10.29 per cent, 14.74 per cent and 12.24 per cent respectively in GM1 and 6.6 per cent, 5.95 per cent and 7.9 per cent, respectively in GM2 higher compared to fallow (Fig. 1). These results are conformity with the findings of Vishwanath et al., 2006; Biradar, 2008, Dordas and Sioulas, 2008; Golzarfar et al., 2011 and Zareie et al., 2011.
Among the green manure treatments GM1 recorded highest Soil N content in 0-15 cm and 15-30 cm (279.51 kg ha-1 and 283.33 kg ha-1, respectively). As compare to rest of the green manure treatments GM2 (266.58 kg ha-1 and 269.74 kg ha-1, respectively) and GM1 (205.28 kg ha-1 and 208.44 kg ha-1, respectively) before sowing of safflower crop (Table 1).
Soil N content at the time of safflower harvest
At harvest, among the green manure treatments GM1 recorded highest Soil N content in 0-15 cm and 15-30 cm (245.15 kg ha-1 and 249.27 kg ha-1, respectively). As compared
to rest of the green manure treatments GM2 (233.24 kg ha-1 and 237.43 kg ha-1, respectively) and GM1 (224.04 kg ha-1 and 228.01 kg ha-1, respectively) (Table 1).