Dynamos operating in the interiors of rapidly rotating planets and low-mass stars might belong to a similar category where rotation plays a vital role. We quantify this similarity using scaling laws. We analyse direct numerical simulations of Boussinesq and anelastic spherical shell dynamos. These dynamos represent simplified models which span from Earth-like planets to rapidly rotating low-mass stars. We find that magnetic field and velocity in these dynamos are related to the available buoyancy power via a simple power law which holds over wide variety of control parameters.

Field experiments were conducted for the three consecutive cropping seasons of 2003–05, 2004–06 and 2005–07 at the Indian Institute of Sugarcane Research, Lucknow, India, to explore the feasibility of planting sugarcane in autumn as a relay intercrop in standing rice. The cropping systems evaluated were: i) rice-potato-spring sugarcane; ii) rice + autumn sugarcane (planted as a relay intercrop in every sixth row devoid (skipped) of transplanted rice + potato after rice; iii) rice-autumn sugarcane (planted without preparatory tillage) + potato; and iv) rice-autumn sugarcane (planted with preparatory tillage) + potato. In each case, sugarcane was planted in rows 90 cm apart. Rice was transplanted in rows at 20-cm row spacing when followed by potato or sugarcane, but at 18-cm row spacing when intended for sugarcane planting as a relay intercrop in late September. The germination (60.4%) of cane buds, tillers (323 000 ha−1) and number (149 000 ha−1), length (225 cm), girth (2.44 cm) and weight (747 g) of millable canes were markedly better when autumn sugarcane was planted with rice as a relay intercrop in comparison to other cropping systems. Similarly, this cropping system produced the maximum cane (111.4 t ha−1) and sugar (13.2 t ha−1) along with sugarcane equivalent yield (216.4 t ha−1). In turn, relay intercropping system with maximum cane production efficiency of 420 kg ha−1day−1 fetched the highest economic returns (Rs. 258 ha−1day−1) and benefit:cost ratio (1.5). Compared with the rice-potato-spring sugarcane cropping system, the relay intercrop of autumn sugarcane in standing rice produced 35.4% more cane and 38.3% more sugar with 24.1% higher returns besides 79.1% energy saving. This practice will not only benefit cane growers and sugar mill owners in tropical and sub-tropical India, but also in other parts of the world where rice and sugarcane are extensively cultivated.

Using the reductive perturbation method, we present a theory for dust–acoustic nonlinear periodic waves, namely dust–acoustic cnoidal waves, in a plasma containing hot electrons and ions, and warm dust grains with varying charge. It is found that the frequency of the cnoidal wave is a function of its amplitude. It is also found that the dust grain charge fluctuation and other plasma parameters modify the properties of the dust–acoustic cnoidal waves. In the limiting case, these dust–acoustic cnoidal waves reduce to the well-known dust–acoustic solitons.

Sugar cane (Saccharum sp. hybrid cv. Co 1148) was planted in October alone and in association with potato (Solarium tuberosum cv. Kufri Chandramukhi), coriander (Coriandrum sativum cv. Sheetal), mustard (Brassica juncea cv. T59) and wheat (Triticum aestivum cv. K816) to find the optimum N dose in alluvial entisols of Lucknow, India. The yield of sugar cane was least in association with wheat and most with potato. The optimum N doses for sugar cane were 152, 175, 186 and 231 kg/ha when grown in association with potato, coriander, mustard and wheat respectively. The optimum N dose for sugar cane grown alone was 186 kg/ha.

To study the response of three sugarcane genotypes (CO 1148, COJ 64 and CO 1158) to variations in moisture availability in sandy loam soil (entisol), field trials were conductedat Lucknow (26·5° N, 80·5° E, 120 m altitude) during 1984–5 and 1985–6. Three moisture regimes, i.e. wet (irrigation at 75% available soil moisture (ASM)), moist (irrigation at 50% ASM) and dry (irrigation at 25% ASM) were maintained during the pre-monsoon (before June) period in spring-planted (February-March) sugarcane. During the summer months (until June)the variety CO 1148 had a significantly greater sheath moisture percentage than COJ 64 and CO 1158. Under stress conditions, leaf area index was reduced most in COJ 64 and least in CO 1148.Underground shoots and roots grew faster in CO 1148, and the growth of above-ground parts was quicker in COJ 64. Compared with the 75% ASM regime the reduction in cane yield in the 25% regime was more in COJ 64 and CO 1158 (31 t/ha) than in CO 1148 (12 t/ha). The water requirement of COJ 64 was greater than that of the other varieties. Therefore, for higheryields COJ 64 needed frequent irrigation whereas CO 1148 performed well even under moderate irrigation (50% ASM).

Opium poppy (Papaver somniferum Linn.) was sown at three sowing dates (10, 25 November, 10 December), row spacings (15, 30, 45 cm) and population densities (6 × 105, 3 × 105, 1·5 × 105 plants/ha) in a split-plot design at Lucknow. Sowing on 10 November resulted in higher yields of opium, seed, total dry matter and morphine content. Delayed sowing, higher plant density and narrow spacing produced low yields with less morphine content. Decline in opium yield was associated with decrease in plant height, leaf area index, capsule size and number of capsules per plant. The crop sown on 10 November removed most N. N concentration and uptake also increased when the number of plants per unit area was decreased. The study suggests that to achieve maximum yields poppy should be sown in rows 30 cm apart on 10 November with 3 × 105 plants/ha.

Two potato genotypes, Kufri Sindhuri (KS) and Kufri Chandramukhi (KC), were grown in association with sugarcane (cv. Co 1148) at 1:1 (SP) and 1:2 (SPP) sugarcane (S): potato (P)row arrangements. Growth behaviour and yield of both crops in companionship were compared with those of their sole cropping. Initially, KC accumulated more dry matter in tubers than KS. At harvest, the contribution of tubers to total dry matter was the same in both genotypes. However, KS produced significantly higher absolute tuber yields than KC. Potato row arrangements in sugarcane did not significantly affect the proportion of dry matter in different plant components. However, SPP gave significantly higher tuber yields than SP and was the same as with sole potatoes. Drymatter accumulation, canopy development and yield of sugarcane were not affected significantly by potato row arrangements in the companion cropping system. Sugarcane was unaffected by KC in companion cropping but KS exerted an adverse effect on all the growth characters and yield of sugarcane. Similarly, in sequential cropping, sugarcane yielded significantly less when planted after KS than after KC.

Japanese mint, an important essential-oil-bearing crop, is cultivated for menthol used in cosmetic and pharmaceutical industries. It requires a high level of nitrogen fertilizer, between 150 and 250 kg N/ha depending on the agro-climatic conditions (Ghosh & Chatterjee, 1976; Yadav, Mohan & Ram, 1983). During the crop cycle (January–August), frequent irrigations and high intensive rains result in poor N recovery especially on light-textured soils. With a view to reduce losses of N and improve N recoveries, the relative efficiency of neem-cake-coated urea, laccoated urea and urea supergranules has been investigated in comparison with prilled urea in Japanese mint.

In a field experiment at Lucknow in 1985/87 and 1986/88, the ‘new’ N carriers urea super granules (USG), neem-cake-coated urea (NCU) and dicyandiamide-treated urea (DCD) and the traditional source of N, prilled urea (PU), were used to supply 150 kgN/ha to the plant crop (first crop after planting) of the cultivar Col 148. The ratoon crop was fertilized at 0 and 150 kgN/ha with PU over all the plant crop treatments. In both plant and ratoon crops, N application increased cane yields but decreased quality: differences in yield resulting from use of the new carriers were not significant, though the fertilizers tended to increase the final plant population density. Uptake and recovery of N were significantly greater using USG, NCU and DCD than using PU. The direct effect of N was 184 kg cane/kg of N applied to the ratoon crop but residual and cumulative effects of N applied to the plant crop on yield and quality of the ratoon crop were small. Adequate direct application of N is therefore suggested for increasing the yields of ratoon cane.

In a 2-year field study conducted at Lucknow (26·5° N, 80·5° E and 120 m altitude), plant height, leaf area index, dry-matter accumulation and N uptake of opium poppy (Papaver somniferum L.) followed a sigmoid path. After attaining a peak of accumulation at 120 days, dry matter declined in plots given N fertilizer but remained static in the control. N application (50, 100, 150 and 200 kg/ha) increased the opium, seed and morphine yields compared with the control. Morphine concentration (%) in the opium, however, increased up to 100 kg N/ha and decreased when N doses exceeded that level. Divided application of N, i.e. half at sowing and remainder at the stem elongation stage, proved beneficial for opium, seed and morphine yields.

Increased demand for steroidal drugs in recent years has prompted a worldwide search for sources of diosgenin other than from species of Dioscorea (Singh et al. 1980). Costus speciosus (Koen.) Sims, an erect perennial herb found growing wild throughout India, has been suggested as one possible alternative source of diosgenin (Dasgupta & Pandey, 1970; Sarin, Bedi & Atal, 1974; Kapahi et al. 1978). Efforts have been made at the Central Institute of Medicinal and Aromatic Plants to increase the diosgenin yield of Costus speciosus by improved agronomic methods. This note is a result of such experiments, in which the effect of different rates of application of N, P and K was studied.

Obliquely propagating ion-acoustic nonlinear periodic waves in a magnetized plasma consisting of warm adiabatic ions and two Maxwellian electron species are studied. Using the reductive perturbation method, the Korteweg–de Vries (KdV) equation is derived and its cnoidal wave solution is discussed. It is found that as the amplitude of the cnoidal wave increases, so does its frequency. The effects of variations in the density and temperature ratios of the two electron species, the ion temperature, the angle of obliqueness and the magnetization on the characteristics of the cnoidal wave are discussed in detail. When the coefficient of the nonlinear term of the KdV equation, a1, vanishes, the modified Korteweg–de Vries equation is derived, and its periodic-wave solutions are discussed in detail. In the limiting case these periodic-wave solutions reduce to soliton or double-layer solutions.

The nitrate–N profile of soil was studied in sole and parallel multiple-cropping systems of pigeonpea and maize and of sugarcane and blackgram. In sole cropping there was more nitrate–N in the deeper horizons because of leaching from the inter-row spaces of row crops, whereas the nitrate content was drastically reduced in parallel cropping at more than 30 cm deep as N in the inter-row spaces was better utilized by the crops. The yield of two crops, when combined, was more in parallel cropping than the sum of crops grown separately, and the Land Equivalent Ratio was higher in parallel-cropping systems than in sole cropping.

In two field experiments conducted over five successive sugarcane crops (including four ratoon crops), yield decline was associated with a decrease in the organic carbon content of the soil. Reduction in cane yield was minimized by the combined application of farmyard manure and urea, which resulted in an increase in soil organic carbon of 0.023% over the initial status within five years. Incorporation of farm waste materials such as cane trash, rice straw and legume husk into the soil before cane planting also increased the soil organic carbon content. Maximum benefits, however, were produced by the incorporation of legume husk with 150 kg N ha−1. A judicious mixture of chemical fertilizer and organic manures is therefore suggested as a means of sustaining the productivity of sugarcane.

In sub-tropical India where 70% of the country's sugarcane is grown, companion cropping of wheat in autumn-planted sugarcane is beneficial. However, because the yield of sugarcane is reduced, farmers there are reluctant to adopt this cropping system in spite of the greater monetary gains compared with wheat-sugarcane sequential cropping. Application of 200 kg nitrogen ha−1 to sugarcane in two doses, two-thirds immediately after the wheat harvest and the remainder a month later, combined with irrigation at 75% available soil moisture during the summer months (April–June), produced cane yields similar to those from sole autumn-planted sugarcane, with an additional 4.8 t ha−1 of wheat.