Effect of Combined Use of Organic and Inorganic Sources of Nutrients on Sunflower Yield,Soil Fertility,and Overall Soil Quality in Rainfed Alfisol

Abstract

To study the response of inorganic and organic nitrogen (N) sources both alone and in conjunction and their influence on soil quality, a field experiment was conducted during kharif and rabi seasons using sunflower (MSFH‐8) as test crop. The experimental site soil was Typic Haplustalf situated at Hayatnagar Research Farm of Central Research Institute of Dryland Agriculture, Hyderabad, India, at 17° 18′ N latitude, 78° 36′ E longitude. The experiment design was a simple randomized block design with 11 treatments replicated four times. Among all the treatments, vermicompost (VC)+Fert at 25+25 kg N ha^?1 recorded the highest grain yields of 1878 and 2160 kg ha^?1 during both kharif and rabi seasons, respectively, which were 43.9 and 85.1% higher than their respective control plots. Apparent N recovery varied from as little as 38.30% (FYM at 50 kg N ha^?1) to 62.16 (25 kg N ha^?1) during kharif and 49.65 (75 kg ha^?1) to 83.28% (VC+Fert at 25+25 kg N ha^?1) during rabi season. Conjunctive nutrient treatments proved quite superior to other set of treatments in improving the uptake of N, phosphorus (P), potassium (K), sulfur (S), and micronutrients in sunflower and their buildup in the soil. Highest relative soil quality indexes (RSQI) were observed under VC+Fert at 25+25 kg N ha^?1 (1.00) followed by VC+Gly at 25+25 kg N ha^?1 (0.87). Considering the yield and relative soil quality indices (RSQI), conjunctive applications of VC with either inorganic fertilizer, FYM, or Gly at 25+25 kg N ha^?1 could be a successful and sustainable soil nutrient management practice in semi‐arid tropical Alfisols. Besides this, the fertilizer N demand could be reduced up to 50%.     

A review of potato propagation by means of seed, as distinct from clonal propagation by tubers

Summary The vast majority of cultivated potatoes are vegetatively propagated, outbred autotretraploids. Disease problems dominate the maintenance of vegetative stocks. There have been recent proposals to propagate the crop by sexual seed in order to evade some of those disease problems. Some success has been achieved but controlled crosses are necessary to avoid inbreeding depression and seed propagation is not as cheap or simple as had been hoped. The idea has evoked wide interest throughout the tropics and has had some (and increasing) practical impact on China, India and Vietnam. There is a strong tendency to use ‘tuberlets’ borne on crowded nursery plants rather than to grow true seedlings. Some seedling families have looked locally attractive but it is not always realised that to use them implies the abandonment of about half the genetic variation, a heavy price to pay for disease avoidance. There is emerging recognition that vegetative and seed propagation are complementary rather than competitive and that good breeding programmes will therefore serve both. This review concentrates upon genetic/plant breeding aspects of propagation by seed, a subject hitherto largely neglected in the literature.     

Structural stability of an Alfisol under various fallow management practices in southwestern Nigeria

The effects of legume‐based soil management on soil dispersion were studied on an Alfisol between 1994 and 1995 in an experiment which was established in 1989 in southwestern Nigeria. The fallow systems, which constituted the main plots in the split‐plot experiment, included natural fallow, Pueraria phaseoloides (Roxb.) Benth, and Leucaena leucocephala Lam de Wit. The subplots were 25, 33, 50 and 100 per cent cropping intensities. Apart from indices of soil dispersion such as water‐dispersible clay and dispersion ratio, the fractal theory was applied to describe the fragmentation of soil aggregates less than 4 mm under the systems and cropping intensities. Although water dispersible clay was less than 60 g kg⁻¹ in the 0–15 cm soil depth because it was inherently low in clay content, the soil dispersion ratio was generally above 50 per cent. Also, the fractal dimensions, which ranged between 2.75 and 2.89, were similar among the fallow systems with cropping intensities for the surface soil. However, the interaction of slope position with season caused significant differences in fractal parameters, suggesting that the processes of soil degradation were different for the upper and lower slopes even with similar microaggregate distribution. The soil was inherently vulnerable to soil dispersion, although, the fallow management systems with less than 100 per cent cropping intensity would maintain soil structure at similar level as the forest. Copyright © 2001 John Wiley & Sons, Ltd.