The actual transpiration of corn (Zea mays L.) was determined by hydraulic lysimeters, by the inflow-outflow method and by use of a neutrone probe. Two irrigation treatments were used; wet and dry. Under the wet treatment, 740, 858, and 743 mm of irrigation water was used during the seasons 1968, 1969, and 1970 respectively. Under the dry treatment, amount of irrigation water used was 560, 627, and 565 mm during the seasons 1968, 1969 and 1970, respectively. Ratios of actual transpiration (Et) to Penman's estimate of potential evaporation (Eo), evaporation from a Class-B pan (EpB), global radiation (Rg) and net radiation (Rn) were calculated. Values of Et measured by the different methods are in good agreement. Seasonal averages of Et, were 6·2 and 4·9 mm/day under wet and dry treatments, respectively. The Et/Eo, Et/EpB, Et/Rg and Et/Rn ratios increased with leaf area index (L.A.I.) and reached their maximum values when L.A.I, reached its maximum value of 1·03 under wet and 0·92 under dry treatment. The empirical coefficient (f = Et/Eo) under wet treatments was found to be higher than that given by Penman for short grasses and about the same as that obtained by Boumans et al. (1963) for golden-gram (Phaseolus aureus) in Iraq for the months August and September. The empirical coefficient Kb in the Blaney–Criddle formula was greater than the value given by Blaney and Criddle for an arid climate, and less than the value obtained by Boumans et al. for golden-gram in Iraq. It was further found that water use efficiency for grain production was greater under dry than under wet treatments.

A major drawback of avocado (Persea americana Mill.) is susceptibility to frosts, which reduces yields and limits its geographic distribution and market growth. Whereas the frost-susceptible cultivar ‘Hass’ leads the global avocado market, cv. ‘Ettinger’, although commercially less important, is considered frost-tolerant. The mechanism behind the greater frost tolerance of ‘Ettinger’ has not yet been elucidated; therefore, the aim of the current study was to evaluate the differences between the frost responses of the two cultivars. The results showed that detached ‘Ettinger’ branches had greater tolerance than ‘Hass’ to controlled frost stress. Tissue browning caused by methyl viologen oxidative cell damage, superoxide accumulation in leaf discs following wounding and browning of cut surfaces in branches were much lower in ‘Ettinger’ than in ‘Hass’, suggesting greater antioxidant activity (AA) in the former. In leaf extracts, AA was significantly higher in ‘Ettinger’ than in ‘Hass’, but osmolarity was similar in the two cultivars. Total phenolics content was significantly higher in ‘Ettinger’ but addition of a protein mask did not significantly reduce AA in either cultivar. Interestingly, following the freezing treatment, AA increased in ‘Ettinger’ and remained almost unchanged in ‘Hass’, while osmolarity was unaffected in either cultivar. These results suggest that the greater frost-tolerance of ‘Ettinger’ than ‘Hass’ is due largely to its greater AA, which springs mainly from a non-enzymatic source, i.e. accumulation of phenolic compounds. Based on the current study, future applications may be developed to minimize frost damage in avocado orchards.

A comparative slaughter experiment was carried out to examine the effects of feeding either grass silage alone or a mixed diet of silage and concentrate on animal performance and the partitioning of nutrients between lean and fat deposition in steers. Eighteen Hereford×Friesian steers were randomly assigned to two dietary treatments; grass silage only (S) or a mixture of grass silage and a barley/soya bean meal concentrate (80[ratio ]20 on fresh basis) in the ratio of 60[ratio ]40 (on a metabolizable energy basis; SC), and to one of three target slaughter liveweights, 250, 350 or 500 kg. Metabolizable energy (ME) intake was maintained at 800 kJ ME per kg metabolic liveweight (kg0·75) per day. The relationships between chemical composition and empty body weight (EBW) at slaughter were assessed using allometric equations (logey=logea+blogeEBW). When assessed across the slaughter weights, supplementing silage with concentrates resulted in higher rates of liveweight (P<0·001), carcass fat (P<0·05) and protein (P<0·01) gains and a reduction in time taken to reach the average slaughter weight by 57 days (P<0·001). Carcass protein deposition was relatively linear across the slaughter weights (250–500 kg) and the relationship with EBW was Y=0·2372X0·8831 across treatments and did not differ between the diets. The rate at which carcass fat was deposited in relation to weight across all steers was Y=0·0004X1·9648 and was not different between the two diets. Hence, ratios of carcass fat[ratio ]protein and carcass fat[ratio ]protein gain ratios were not different. The results suggest that the main effect of feeding grass silage compared with grass silage-concentrate at similar levels of ME intake was to increase the rate of tissue accretion, but nutrient partitioning between fat and protein deposition was unchanged. There was no evidence of increased carcass fat[ratio ]protein deposition in silage-fed animals, which suggests that there is no problem of greater fat and reduced protein deposition in animals fed higher quality grass silage.

Results of two in vivo sheep experiments in which gamma-irradiated material in teryleno bags was fermented in the rumen are reported.

Exp. I concerned the testing of rice straw, nassella (Nassella trichotoma) and cotton lint, each subjected to six dose levels of gamma irradiation (0, 5, 10, 25, 100 and 200 Mrad) when wet and when in the dry state. The tests were made in sheep fed either a lucerne hay or a rice-straw base diet.

Dry -matter disappearance of all test materials was influenced by irradiation treatment: levels of 10 and in some instances 25 Mrad depressed, and other levels substantially enhanced, intraruminal degradation rate tested over 72 h. Materials irradiated in the dry state were better dissimilated than those irradiated in the wet state.

On severe shaking for 14 h in water, solubility values as high as 35 % were obtained for irradiated test materials receiving the highest dose of irradiation but such values were never of the same magnitude as total dry-matter losses in the rumen. When irradiated material was immersed in gently flowing water for 12 h solubility values of 1 % were found for material dosed at 100 or 200 Mrad and of nil for other dose levels. At no level of irradiation was solubility depressed. It was concluded that enhanced losses of irradiated dry matter in the ruminal environment arose substantially from fermentation.

Intraruminal dissimilation of irradiated test material from terylene bags was always greater on lucerne hay base diets than on rice straw base diets.

Exp. II investigated the influence of urea supplementation, at levels of 1 % and 2 % of diet, on the dissimilation of irradiated test samples of cotton lint and rice straw for sheep fed a rice-straw base diet.

Similar effects of irradiation on cotton lint and rice straw to those found in Exp. I were observed. Overall, urea supplementation depressed dissimilation rate of rice straw and severely depressed degradation of cotton lint irrespective of irradiation dose up to an irradiation dose level of 100 Mrad. It is concluded that urea supplementation per se depressed the activity of cellulolytic organisms.

It is considered that feeding trials with low-quality roughages irradiated at levels at or greater than 25 Mrad are warranted.

The effects of environment and genotype on growth and yield of cotton were studied in three experiments done at Namulonge, Uganda, from 1966 to 1969. Treatments were date of sowing, variety, fertilizer, plant population and water. Variety BPA66 sown in June at 4–10 plants m-2 outyielded other varieties, sowing dates and population densities. Compound fertilizer at l.25 t ha-1 increased yield by 15% and irrigation increased yield by 38%. The soil water deficit (CSWD) was calculated from meteorological data, and the relative water content (RWC) of the plants was measured. CSWD did not affect growth until a critical value (CD) was reached, which increased from 20 to 50 mm as the crop aged. When CD was reached RWC was s0·094 at dawn and 0·83 at 1400 h. Growth stopped when CSWD > CD, except while any rain, insufficient to make CSWD < CD, was being consumed. Days while such rain was being consumed and days when CSWD < CD were added to give the effective numbers of growing days which accounted for differences in numbers of mainstem nodes caused by sowing date and spacing, and for differences in plant dry weight and leaf area caused by sowing date. Variation in light transmitted by the crop canopy depended on leaf area index (L) alone; spacing, fertilizer and CSWD had no independent effects. The measured extinction coefficient was 1.1 compared with 0·9 predicted by de Wit's (1965) model. Measured value of crop growth rate (C) agreed with values predicted by the de Wit model for the vegetative phase. Spacing and fertilizer only affected C through L. During the reproductive phase C became much less dependent on L, and the form of the relationship changed. Some varieties including BPA66 had a greater net assimilation rate. Maximum C was expected when L ~ 3, but L was seldom > 2. Crops sown at current and previously recommended spacings had sparse canopies and did not fully use light available for dry matter production.

1. Observations have been made of the seedling reactions of species of Triticum and Aegilops and of amphidiploids between them to races of Puccinia glumarum, P. triticina, P. graminis and Erysiphe graminis. These observations have been compared with field observations on mature plants. The work on P. graminis and much of that on P. triticina was carried out by Dr R. C. McGinnis of the Dominion Rust Research Laboratories, Winnipeg, Canada.

2. Seedling and mature plant resistance to P. glumarum has been found in Triticum monococcum, Aegilops caudata and A. ovata. Resistance was not shown by amphidiploids of T. monococcum and A. caudata with susceptible species of Triticum, but was shown by some amphidiploids involving A. ovata; T. timopheevi and A. speltoides were susceptible to certain races as seedlings but resistant as mature plants in the field.

3. Seedling resistance to all the races of P. triticina used in these investigations was shown by A. caudata and resistance to certain races by certain other species. Amphidiploids involving A. caudata were resistant to all races, but other amphidiploids were resistant to some races and susceptible to others.

4. Seedling and mature plant resistance to P. graminis was shown by A. caudata. A. ovata and A. speltoides were resistant as mature plants, and only slightly infected as seedlings. None of the amphidiploids tested was completely resistant at the seedling stage; certain amphidiploids involving these three species were, however, only slightly infected as mature plants, and may be useful as sources of resistance to race 15B.

5. Resistance to E. graminis was shown by T. carthlicum, T. dicoccum, T. timopheevi and by numerous species of Aegilops. Amphidiploids of T. carthlicum, T. dicoccum, T. timopheevi and A. caudata with diploid wheat species were resistant to E. graminis, but those with susceptible tetraploid wheats were susceptible. Other intergeneric amphidiploids (with two exceptions) were resistant.

The improvement of milk production by the establishment of four specialized lines and subsequent within-line selection over a 7-year period under grazing conditions at Kraim station in mid-Syria is described. The specialized line showed a substantially higher total milk production amounting to a mean 25% superiority over the control line in 1979–81.

The heritability of total milk yield as estimated from paternal half sib analyses was 0·53 ± 0·169 for 2-year-old ewes and the genetic correlation of a single maximum daily yield record (+ 0·93) with total yield indicates the possibility of simplified selection procedures for this trait.

The effect of several other factors (for example, ewe age and season of lambing) on various aspects of lactation in Awassi ewes is reported.

Four systems of harvesting grass for silage were evaluated in terms of in-field losses, in-silo losses and milk output per hectare. The systems were: single-chop flail harvester direct cutting (SCD); doublechop flail harvester direct cutting (DCD); mown with a rotary mower and picked up with a precisionchop harvester either immediately (PCU) or after wilting until the dry-matter concentration had increased by approximately 100 g/kg (PCW). The in-field and in-silo losses were measured at each of three consecutive harvests during 1984 and during the following winter the resulting silages were evaluated through eight British Friesian cows in a balanced change-over design experiment using four periods each of 5 weeks duration.

There was a greater quantity of herbage ensiled with the two direct cutting systems (SCD and DCD) than with the systems involving pre-mowing and picking up with the ensiled yields, being 12·4, 11·8, 10·8 and 10·8t OM/ha for the SCD, DCD, PCU and PCW systems respectively. These differences were only partly reflected in greater mechanical in-field losses with the pre-mown systems.

Losses during the in-silo period tended to be greater with the wilted than the unwilted silages being 98, 76, 83 and 132 g/kg OM with the SCD, DCD, PCU, and PCW systems, respectively.

Animals offered the PCW silage tended to have a higher silage organic-matter intake and had a significantly higher milk yield than those offered the other silages with fat corrected milk yields being 25·1, 24·5, 24·5 and 25·9 kg/day for the SCD, DCD, PCU and PCW systems, respectively. Milk outputs per hectare, at 30·3, 27·8, 25·7 and 240 for the SCD, PCD, PCU and PCW systems respectively, was lowest for the PCW treatment.

Cultivars of Phleum pratense, Festuca pratensis, Festuca arundinacea, Dactylis glomerata and Lolium × Festuca hybrids were exposed to 4- and 3-cut harvest systems in Prince Edward Island, Canada, in 1985–87. Lolium perenne × F. pratensis, Lolium multiflorum × F. pratensis and L. multiftorum × F. arundinacea hybrids and D. glomerata had more uniform growth among the harvests than other grasses during the growing season. L. perenne × F. pratensis and L. multiflorum × F. pratensis had lower contents of neutral and acid detergent fibre than other grass cultivars, particularly early in the growing season. P. pratense cv. Farol had the lowest and L. perenne × F. pratensis cv. Prior the highest tiller population density. The stem apex of all cultivars was above the cutting height of 5 cm in c. 50% of tillers of primary growth. Leaf area per tiller was largest for P. pratense cv. Farol in the primary growth stage but differences were small in subsequent cuts.

The experimental results submitted in the preceding pages may be summarised as follows:

Seven English soils have been examined in order to ascertain the validity of Greig Smith’s claim that partial sterilisation effects may be due to the destruction of bacterio-toxins in the soil. The results obtained with six of these soils show that:

1. The untreated extracts of these soils varied largely in their suitability for the growth of the test organism (B. prodigiosus). In some instances vigorous growth occurred; in others the numbers of introduced organisms fell to a minimum.

2. Treatment of the extracts by heat (which was supposed to result in the destruction of “toxins”) invariably led to still further bacterial decreases.

3. Extracts of soils treated with antiseptics (which are not supposed to destroy “toxins”) were on the whole more favourable for growth than those of untreated soils. Such extracts were found to have appreciably more organic nitrogen compounds than extracts of untreated soils.

Detailed representation of ingesta inflow to and digesta outflow from the rumen is critical for improving the modelling of rumen function and herbage intake of grazing ruminants. The objective of the current work was to extend a mechanistic model of a grazing ruminant, MINDY, to simulate the dynamic links between ingestive and digestive processes as affected by forage and sward features (e.g. sward structure, herbage chemical composition) as well as the internal state of the animal. The work integrates existing aspects of forage ingestion, oral physiology and rumen digestion that influence ingesta characteristics and digesta outflows from the rumen, respectively. The paper describes the structure and function of the new development, assessing the new model in terms of dynamic changes of oral processing of ingesta and rumen dilution rate under different grazing contexts. MINDY reproduces characteristics of ingesta inflow to and digesta outflow from the rumen of grazing ruminants, achieving temporal patterns of occurrence within and between meals, similar to those for grazing animals reported in the literature. The model realistically simulates changes in particle size distribution of the ingestive bolus, bolus weight and rumen dilution rate in response to contrasting grazing management regimes. The new concepts encoded in MINDY capture the underlying biological mechanisms that drive the dynamic link between ingestion and digestion patterns. This development advances in the understanding and modelling of grazing and digestive behaviour patterns of free-ranging ruminants.

The response of linseed to treatment with two plant growth regulators (PGRs), chlormequat and ethephon, applied at a range of growth stages (corresponding to average mainstem lengths of 10, 23, 46, 55 and 64 cm) and in various combinations (single and repeated applications of chlormequat and ethephon, either alone or mixed) was studied in field experiments over two seasons in 1992 and 1993 at the University College of Wales, Aberystwyth. Reduction in mainstem length was dependent upon the type of PGR and the timing of its application. Chlormequat alone was consistently more effective than ethephon alone, while a mixture of the two at half rates was similar to chlormequat alone. The largest reductions in mainstem length (16·6% with chlormequat and 6·1% with ethephon, averaged over the two years) were achieved when the PGRs were applied when mainstems averaged 22–23 cm in length. Response to PGRs became progressively smaller with later applications. However, the reduction in mainstem length, when expressed as a percentage of that part of the stem yet to extend (i.e. final untreated stem length−stem length at the time of PGR application), was shown to be remarkably consistent across all (apart from the first) timings of application, with average values of 28·4 and 7·4% for chlormequat and ethephon respectively.

Application of both PGRs increased tillering and increased significantly the number of stems per unit area at maturity. This response occurred irrespective of timing of application and was greater following treatment with ethephon than with chlormequat. In the first year, the effects of PGRs on dry matter production and seed yield were small and not statistically significant. In the second year, significant reductions in seed yield were associated with those PGR treatments which promoted tillering most, i.e. early application of ethephon. Smaller yields were the result of fewer capsules per plant. Furthermore, a significant correlation between mainstem length and the number of seeds per capsule indicated a reduction of 0·78 seeds per capsule for every 10 cm reduction in stem length. While total oil content of seed remained unaffected by PGR applications, treatments which included chlormequat at an early growth stage (either alone or in combination with ethephon) altered the relative proportions of fatty acids, reducing the content of linolenic acid while increasing that of oleic acid.

In three field trials, three varieties of cow pea (Prima, Ife Brown and Vita-5) grown as mono-crops or interplanted with maize (in one trial) were sprayed with a combination of PKS or NPKS in solutions containing 100, 100, 100 and 41 mg/1 of N, P, K and S respectively at the onset of flowering or 2 weeks later, in order to evaluate the effect of foliar spray of mineral nutrients on the performance of the crop.

Early season sprayings of NPKS and PKS increased vegetative development and dry-matter accumulation in both mono- and mixed-croppings of Prima and Vita-5, but had little effect on Ife Brown. Seed yield was increased by 80–225 kg/ha in Prima and 160–218 kg/ha in Vita-5. In all cases of enhanced growth and yield, spraying at flowering was more beneficial than spraying 2 weeks later whilst NPKS evoked greater responses than PKS.

In two late-season trials, all treatment combinations enhanced vegetative development and dry-matter accumulation in Ife Brown and Vita-5. Seed yield of Ife Brown was increased by 206 kg/ha in the first late season and by 550 kg/ha in the second late season whilst that of Vita-5 was increased by 226 kg/ha in the first late season, during which it was planted. In the first late season of Ife Brown, late spraying was more beneficial than early spraying, whilst plants sprayed with PKS out-yielded those sprayed with NPKS. On the other hand, in the second late season, Ife Brown responded more to early spraying than late spraying and NPKS was more beneficial than PKS: Vita-5 grown in the first late season responded similarly.

In all cases of enhanced seed yield during the seasons, the pathway of response was through increased pod production and/or retention on the plants. The results therefore suggest that foliar spray of nutrients during the post-flowering period enhance seed yield in cow pea by ensuring prompt delivery of mineral nutrients to the site of photosynthesis at a time when nutrient depletion in the leaves and reduced efficiency of mineral nutrient uptake by the roots limit the supply of photosynthates to developing reproductive organs.

Plasma volume, haematocrit, and haemoglobin concentration were measured in 34 sows. Red cell volume and total blood volume were calculated from plasma volume and haematocrit.

The method of back extrapolation of the logarith of Evans blue concentration to zero time possibly overestimated plasma volume. Haematocrit was found to be higher and more variable in the initial blood samples in each experiment, than in the blood samples taken 30 and 60 min later.

In animals of the same parity, plasma and red cell volumes were closely related to live weight, but the relationship varied between parities.

Soils from Broadbalk field were used to find whether differences in K-manuring had altered K:Ca exchange relationships during 100 years cropping with wheat, by measuring cation exchange capacities and quantity/intensity (Q/I) relationships.

Cation exchange capacities (CECs) were measured with and without the contribution of the soil organic matter and the following mainly non-significant trends arose during 100 years: (1) The CECs of plots given K fertilizer increased slightly when the organic contribution is included and decreased slightly when it is not. (2) The CEC of the plot given farmyard manure increased greatly when the organic contribution is included and decreased slightly when it is not. (3) The CEC of the unfertilized plot increased very slightly, whether or not the organic contribution is included.

The K buffer capacity, the slope of the Q/Icurve when the soil neither gains nor loses K, was related to the K saturation of the CEC better when the organic contribution was omitted from the CEC than when it was included, suggesting that K: Ca exchange measured by the Q/Icurves occurs mainly on the non-organic part of the CEC. Two soils depleted of K had anomalously large buffer capacities, but two undepleted samples behaved similarly.

Superimposing Q/Icurves by eye showed no appreciable differences between samples from different years or from different plots, even at large activity ratios. Plotting exchangeable K against I0, the activity ratio when the soil neither gains nor loses K, gave a single curve embracing all plots from all years, similar to the superimposed Q/I curves. Long–term manuring with ammonium sulphate has not affected K–Ca exchange.

The fate of 35S-labelled sheep urine sulphate in the soil and its plant uptake were measured in field experiments over a 12 month period in 1990/91 in Canterbury, New Zealand. Urine was applied in either summer or winter. After the summer application, there was a marked increase in pasture growth and S uptake which lasted for a period of c. 90 days. Plant uptake of applied 35S was very rapid and c. 11% was recovered in the pasture herbage within 65 days of application. By the end of the experiment, c. 80% had been recovered in the herbage. A portion of applied 35S was incorporated into soil organic forms mainly as C-bonded S. After 86 days, 30% of the applied 35S was in the C-bonded form but during the rest of the experiment this declined to 17% as the 35S was remineralized and absorbed by the growing pasture plants.

Following the winter urine application, the increase in pasture dry matter production and 32S uptake was much less marked than that for the summer application. Twenty five percent of the applied 35S was recovered in pasture herbage within 65 days and this increased to 70% by the end of the experiment. Some of the applied S was incorporated into soil organic forms and, by 83 days, 20% of the applied 35S was present in C-bonded form. Through mineralization this declined to 7% by the end of the experiment. Over the initial 41 days of the experiment, c. 25% of the 35S was lost due to leaching.

1. The high grain-yielding capacity and low total nitrogen content of predominant British varieties of barley, in conjunction with high ear survival at harvest, are discussed.

2. The results of a series of quantitative comparisons in which increased tillering was promoted by the application of nitrate of soda at various phases of plant development, and similarly when tillers were removed at various stages, were examined.

3. It was shown that the effect of nitrogen on the yield and quality of the grain depends upon the time in relation to the stage of plant development at which it was applied; the early applications enhanced the yield without detriment to the quality of the grain, whilst the later applications did not increase the yield but increased the total nitrogen content, and consequently reduced the malting quality of the grain.

4. The increase in yield was obtained primarily by an increase in the number of surviving tillers and to a less extent by an increase in yield of grain per ear; the latter was in some cases accompanied by an increase in 1000-grain weight. High ear survival in varieties such as those under examination may consequently be regarded as an index of high yield of grain and of low total nitrogen content.

5. The removal of tillers resulted in increased total nitrogen content and increased 1000-grain weight in the grain of the main stem; the former was not affected by the stage of development of the plant at which abscission was made, but the highest value of the latter was obtained when the abscission was made before flowering.

6. The relation of 1000-grain weight and nitrogen content was discussed, and it was shown that high 1000-grain weight may exist with both high and low total nitrogen. Although the 1000-grain weight is an hereditary attribute it is subject to considerable fluctuation and cannot by itself be usefully employed as an index of nitrogen content, and consequently of malting quality, in either an inter- or intra-varietal sense.

1. An account has been given of the percentages of nutrients in the dry matter and weights of nutrients in tops, tubers and roots of potato plants throughout growth under six fertilizer treatments.

2. Manurial treatment affected dry-matter content of tops but not of tubers.

3. Balanced manuring, as represented by N2PK treatment, resulted in tubers in which nitrogen content of dry matter declined with age. The effect of the K was to lower the nitrogen, phosphorus and calcium contents, to increase chlorine content of all parts of the plant, and to maintain a much higher and more constant concentration of potassium in tops and roots. With unbalanced manuring the nitrogen content of the tubers was more constant.

4. Manuring with nitrogen only raised the content of potassium in the dry matter of all parts of the plant.

5. Nitrogenous manuring, whether alone or in combination, raised the nitrogen content of the dry matter of all parts of the plant, a smaller proportion of which was present as protein. Calcium and chlorine contents were lowered.

6. Phosphate manuring in conjunction with nitrogen depressed the concentration of potash in the dry matter of all parts of the plant.

7. N2P plants were the first to attain their maximum uptake of all nutrients, namely, about 7 weeks from appearance above ground, at which time N2PK plants had absorbed only 40% of the quantities finally noted.

8. No losses of elements were observed in the plants which received balanced manuring (N2PK), but losses of calcium and chlorine occurred in all other plants, amounting on the average to 25 and 37% respectively, but being highest in N2P plants. A significant loss of potassium occurred in N2 plants and a highly suggestive loss of phosphorus occurred in N2P plants.

The effects of farmyard manure (FYM) and P and K fertilizers on soil properties were studied at the end of a 3-year (1972–5) field experiment at New Delhi, India. Each year a crop of rice and wheat was grown. FYM was applied at 0 or 15 t/ha, phosphorus at 0, 30 and 60 kg P2O5/ha and potassium at 0 or 60 kg K2O/ha. Treatments included application of manure and fertilizer to rice or wheat alone or to both the crops. FYM application increased organic C, total N and available K and P in the soil, the effects being greater when both rice and wheat received FYM. Application of FYM slightly decreased the soil pH. Phosphorus and potassium fertilizer increased available P and K in the soil, respectively.

Sugarcane (Saccharum spp.) ratoon crops comprise more than 0·50 of India's sugarcane acreage and reduce the cost of cultivation by 25–30%. However, ratooning is seldom practised beyond 1–2 ratoons because the yield declines in successive ratoons due to compacted soils with decreased fertility restricting root development and plant growth. Therefore, a field experiment on sugarcane was conducted from 1998 to 2003 at the Sugarcane Research Institute, Muzzaffarnagar (Uttar Pradesh), India to evaluate the effects of combinations of trash management with key cultural practices (stubble shaving, ridge dismantling, sub-soiling along stubble rows, trash mulching and earthing-up) on growth and yield of sugarcane up to the third ratoon. Two treatment combinations (ridge dismantling+stubble shaving+sub-soiling along stubble rows+trash mulching at 8 t/ha (T5) and all these plus earthing-up in June (T6)) showed similar growth, yield and economics of ratoon crops. Both these treatments produced significantly higher shoot populations, leaf area index (LAI), dry matter (DM) accumulation, net assimilation rate (NAR), number of millable canes, ratoon cane yield and sugar, soil organic carbon (SOC) content at harvest and higher net returns besides lowering weed density, weed dry weight and bulk density of soil compared with other treatments. T6 produced the highest cane yield of 77, 72 and 65 tonnes (t)/ha, which was 23, 27 and 29% more than trash burning alone (T1) in first, second and third ratoon crops, respectively. Although T6 had the same yield as T5, it led to significantly lower soil bulk density at 0–150 mm depth, higher SOC contents and greater benefit: cost ratios in the first, second and third ratoon crops, respectively compared with trash burning only. Adoption of the crop management components, separately or in combination, improved on trash burning only (the control treatment). Trash mulching sustained the improved yield and economic returns of sugarcane ratoon crops.