Six fertilizer–nitrogen sources, each at three levels, together with a control of no fertilizer–nitrogen were compared in field trials in two consecutive crop seasons on a sandy soil comparatively deficient in nitrogen at Patna, Bihar. Four mathematical models were fitted to the potato yield data in order to evaluate the relative availability indices of the individual fertilizers. Data collected on final stand and ‘emergence rate’ index (Bartlett) showed that while urea applications gave rise to a comparatively low speed of emergence, with observed shoot injuries, nitrate of soda caused poor final stands. The other fertilizers had no effect on either the final stand or the speed of emergence.

Sulphate of ammonia was chosen as the standard fertilizer for the present study. Ammonium sulphate nitrate was as good as or even slightly better, while ammonium chloride and calcium ammonium nitrate were of intermediate efficiency, in that order. Urea and nitrate of soda were decidedly poor as nitrogen sources for potatoes under the conditions of the study. The concurrent Mitscherlich curves model was found to represent the behaviour of these fertilizers with a good measure of fit.

The performance of the six fertilizers is discussed in the light of the availability of NH4+ and NO3-, the phytotoxicity of urea and nitrate of soda, and the harmful effects of Cl-. It is concluded that ammonium sulphate nitrate is the best carrier of nitrogen among those studied for potatoes under the conditions set forth.

The present paper compares standard and novel methods for analysing aggregated patterns of plant death in designed field experiments; these methods include binomial (BN), beta-binomial (BBN), logistic-normal-binomial (LNB), BN models with random blocks, BN models with smooth-scale spatial components and principal coordinates of neighbour matrices (PCNM). PCNM is a relatively new technique used in ecology to determine how much observed variability can be explained by spatial and environmental variables, and has not yet been applied to agricultural studies. The survival data of two pasture species, collected from a designed field experiment that was replicated at multiple locations, were used. First, the occurrence of overdispersion was tested using the BN and BBN distributions. Goodness-of-fit tests proved that the BBN model provided a better description (better fit) of the observed data in some cases than did the BN distribution, indicating overdispersion was present. When overdispersion was not present, the BN distribution was adequate to describe the data, and the use of the BBN distribution was superfluous. It is then shown that the PCNM approach, the BN model with smooth-scale spatial components and the LNB model were able to account for some of the variation as spatial variability, thus reducing the species effect compared with that explained under the standard BN model. The amount of variation among species according to the BN model and the BN model with random blocks was similar. Therefore, it is argued that the novel PCNM approach warrants further testing when exploring the spatial variability in designed experiments in agriculture and using LNB, PCNM and BN with smooth-scale spatial components may provide better predictions of species effects than do other, more conventional, approaches.

Mechanical peeling of potatoes removes an exceedingly thin skin that is notably richer in ether extract, fibre and lime, but much poorer in N-free extractives, than the thicker parings obtained by ordinary hand peeling. The latter, in respect of their general composition, do not differ to any marked extent from whole potatoes.

The results of digestion trials with pigs have shown that potato peelings, after cooking, are highly digestible when included in the rations of bacon pigs. The N-free extractives, which form about 80% of the dry matter of the hand peelings, have a digestion coefficient of 96·2%. An allowance of 5 lb. of such peelings supplies as much digestible organic matter as 4 lb. of whole potatoes, and it is concluded that 1 lb. of barley meal in the rations of bacon pigs may be replaced by 4 lb. of potatoes or by 5 lb. of potato peelings. Both the potatoes and the potato peelings should be cooked before feeding.

In conclusion, the writers take this opportunity of expressing their thanks to Messrs V. Thurlbourn and C. Bendall, in whose experienced hands the care of the experimental animals was placed during the digestion trials.

The rumen was found to be the main site of metabolism of biuret in sheep adapted to this compound. Some of the biuret which passed into the lower gut could be broken down there but this could account for the breakdown of less than 1 g/day when 15 g was fed. Biuret injected into the jugular vein or entering the bloodstream from the rumen or intestine was excreted unchanged in the urine. Sheep excreted 9–21% of biuret fed in a solid form and 37–39% when it was dosed as an aqueous solution. Sheep not adapted to biuret failed to retain any introduced into the rumen, duodenum or jugular vein.

Mineral analyses for calcium and phosphorus were carried out on lambs which had been fed diets contrasting in protein or energy or calcium concentration and had been slaughtered at defined live weights. Despite considerable variation in rates of growth arising from the widely different nutritional programmes, the mineral content of these lambs at a given weight remained remarkably stable on practical diets.

A 2-year field study to investigate the potassium nutrition of groundnut in the lowland tropics showed that a low rate of K is beneficial to the crop. Applied K significantly increased leaf N, seed S, seed P, seed Fe, seed oil and protein content of groundnut. Leaf Ca significantly decreased with increased K application but K treatments significantly increased the seed and shell Ca. Potassium and Ca concentrations were highest in the leaf and lowest in the shell and seed respectively. The significant increases in shell P, shell Ca and shell Fe with increased K application would greatly improve the groundnut shell quality as an animal feed component. The relationship between seed oil and protein content was positive and significant.

The mean concentration of plasma albumin in 30 Finnish Landrace x Dorset Horn ewes subjected to intensive breeding decreased as the number of pregnancies increased from three to seven; it also changed significantly within a pregnancy. Gamma globulin concentration was not affected by the number of pregnancies but decreased significantly within a pregnancy. Total plasma protein was affected like albumin by the number and stage of pregnancy.

Plasma volume increased by 23 % in the latter third of pregnancy.

1. A small-scale experiment in which cows have been fed at three levels for 3 weeks during mid-lactation has been carried out.

2. The results show that the changes in milk yield due to changes in the level of feeding were relatively small.

3. It has been suggested that where short-term food shortages occur in well-fed herds, economy should take place in the rations of the cows in mid-lactation rather than in the ration of the cows which are soon due to calve.

Differences in the partitioning of fat in the carcass may affect ‘carcass quality’ and depending upon the particular market requirements the optimum partitioning of fat may vary. Differences in fat partitioning may also affect the accuracy with which total carcass fat can be predicted from an assessment of subcutaneous fat (Pomeroy & Williams, 1974).

Although application of organic fertilizers has become a recommended way for developing sustainable agriculture, it is still unclear whether above-ground and below-ground crops have similar responses to chemical fertilizers (CF) and organic manure (OM) under the same farming conditions. The current study investigated soil quality and crop yield response to fertilization of a double-cropping system with rapeseed (above-ground) and sweet potato (below-ground) in an infertile red soil for 2 years (2014–16). Three fertilizer treatments were compared, including CF, OM and organic manure plus chemical fertilizer (MCF). Organic fertilizers (OM and MCF) increased the yield of both above- and below-ground crops and improved soil biochemical properties significantly. The current study also found that soil-chemical properties were the most important and direct factors in increasing crop yields. Also, crop yield was affected indirectly by soil-biological properties, because no significant effects of soil-biological activities on yield were detected after controlling the positive effects of soil-chemical properties. Since organic fertilizers could not only increase crop yield, but also improve soil nutrients and microbial activities efficiently and continuously, OM application is a reliable agricultural practice for both above- and below-ground crops in the red soils of China.

Ten varieties of field beans, grown in different environments, were analyzed for genotypic stability of their seed yield. The linear responses to the environments were insignificant, but deviations from linearity were highly significant suggesting that the relatively unpredictable component of the genotype x environments interactions was more important in this material than the relatively predictable component. Environmental effects per se were very important in determining differences in mean seed yield. The relatively large deviations from linearity of variety IW may be due to powdery mildew disease. RB 29 was identified as a good yielding and stable variety in the range of environments tested.

The effects on emergence and growth of crisp lettuce seedlings as a result of sowing seeds at different depths and pressing them into the furrow bottom with a weighted seed press wheel were examined in three similar experiments in 1982, 1983 and 1984. Sowing depth had a considerable effect on percentage seedling emergence and the spread of emergence times but the pattern of response varied from year to year and appeared to be related to differences in soil moisture content. The most uniform emergence and the highest level of emergence were achieved by sowing shallowly (< 10 mm) with rainfall almost immediately after sowing then keeping the soil moisture content close to field capacity for 2 days. When rainfall or irrigation were delayed, drilling 15–20 mm deep gave more consistent results. Effects on seedling weight and variability of weight were associated with the time and uniformity of seedling emergence. Later emerging seedlings were lighter and a wide spread of emergence times gave seedlings of variable weight. There was virtually no effect on emergence of using additional weights on a seed press wheel.

1. Milk and butterfat production rise to about the sixth lactation, but beyond the fifth lactation the increase may be neglected.

2. The lactation of maximum production may be taken as the fifth which corresponds to 7 years of age.

3. Beyond the fifth lactation the milk and butterfat yields vary irregularly but show a downward tendency.

4. The fat yield shows either a fall or only a very small increase in the second lactation.

5. The fat percentage is highest in the first lactation, drops markedly in the second, remains fairly steady for a few lactations, though with a slight downward tendency, and then falls off in the higher lactations.

6. Results obtained by applying correction factors for either age or lactation are quite comparable and choice in the method to be used will depend largely on the original data available.

The technique of regression on environmental index is used to examine the behaviour of varieties in monoculture and mixture. It is shown that, sometimes, single regressions for each variety do not provide an adequate explanation of the interactions between varieties and environments.

The effects of controlled grazing, application of N, P, K, Ca, and Mg and the introduction of grasses and white clover, with and without cultivations, on Molinia caerulea dominant rough hill grazing were studied over 19 years in mid-Wales. Nutrient concentration in, and uptake by, the herbage and changes in soil physical, chemical and biological characteristics were monitored periodically. Concentrations and uptake of N, P, K, Ca, Mg and Na were highest on the reseeded pastures. Nutrient balance sheets showed that the nutrients applied were most efficiently utilized on reseeded swards. They also highlighted the considerable losses of applied Ca and Mg that occurred.

Implications of the results are discussed in relation to both future agricultural use of such areas in the hills and the effects on the environment.

This study aimed to examine the effects of re-ensiling time and Lactobacillus buchneri on the fermentation profile, chemical composition and aerobic stability of sugarcane silages. The experiment was set up as a repeated measure design consisting of four air-exposure periods (EP)(0, 6, 12, and 24 h) microbial additive (A) (L. buchneri; or lack of there), with five replicates. Sugarcane was ground through a stationary forage chopper and ensiled in four plastic drums of 200-L capacity. After 210 days of storage, the drums were opened and half of the silage mass was treated with L. buchneri at the concentration of 105 cfu/g of forage. Subsequently, the silages were divided into stacks. The re-ensiling process was started immediately, at 0, 6, 12 and 24-hour intervals, by transferring the material to PVC mini-silos. Silos were opened after 120 days of re-ensiling. The use of L. buchneri reduced butyrate concentration but did not change ethanol or acetic acid concentrations and aerobic stability. An interaction effect between L. buchneri and re-ensiling time was observed for dry matter (DM) losses and composition. Lactobacillus buchneri is not effective in improving aerobic stability in re-ensiled sugarcane silages. However, less DM is lost in silages treated with L. buchneri and exposed to air for 24 h. Re-ensiling sugar cane in up to 24 h of exposure to air does not change final product quality.

Solutions were made by extracting the soils from certain of the Rothamsted plots on which wheat and barley had been grown for 60 years and upwards. Wheat and barley were grown in these solutions, which were renewed fortnightly. The comparative growth in the solutions was closely parallel to the growth of the crop on the plots in the field and corresponded to the composition of the solutions. The composition of the solutions as regards phosphoric acid and potash corresponded to the past manurial treatment of the soils and to the amount of phosphoric acid and potash they now show on analysis. Growth in the soil solutions agreed with the growth in artificial culture solutions containing equivalent amounts of phosphoric acid and potash. Growth in the soil solutions from imperfectly manured plots was brought up to the level of that in the solutions from completely manured plots on making up their deficiencies in phosphoric acid and potash by the addition of suitable salts. The phosphoric acid and potash content of the soil solutions was of the same order as the phosphoric acid and potash content of the natural drainage water from the same plots.

Wheat grew as well as barley in the solutions of the wheat soils, and vice versâ. In a similar set of solutions from the same soils the growth of buckwheat, white lupins and sunflowers corresponded with that of wheat and barley. Boiling effected no alteration in the nutritive value of the soil solutions.

In nutritive solutions of various degrees of dilution the growth of plants varied directly, but not proportionally, with the concentration of the solution, though the total plant food present in the solution was in excess of the requirements of the plant. When the nutrient solution was diffused as a film over sand or soil particles, as in nature, there was no retardation of growth due to the slowness of the diffusion of the nutrients to the points in the liquid film which had been exhausted by contact with the roots. Growth in such nutrient solutions forming a film over sand particles was much superior to the growth in a water culture of equal concentration, but the growth in the water culture was similarly increased if a continuous current of air was kept passing through it.

Five perennial fodder crops and maize were grown for 11 years or more in unfertilized soil. The effect of rainfall, annual and seasonal, and age from planting was examined in detail. Increased rainfall, whether annual or seasonal, led to increased yields of all crops, although the extent of the increase depended on the type of crop, the nature of the rainy season, whether long or short, and in particular the age of the perennial crops. All the perennials aged at similar rates and ageing led to reduced yields. The depressing effect of age is thought to be due to overcrowding and possibly a concealed loss of fertility.

The response of cotton (Gossypium hirsutum L.) to chilling temperatures has been documented mainly for germinating seeds and young seedlings (Christiansen, 1963; Christiansen & St John, 1981; Guinn, 1971; Sellschop & Salmon, 1928). Ratoon (known also as stub or biennial) cotton offers an opportunity to study the chilling injury of mature plants under field conditions. Observations showed that ratooning plants suffer stand loss during the winter. However, the surviving plants recover and start growing vigorously when temperatures rise, early in the following spring (Ellern, 1966; Evenson, 1970; McClintic, 1981).

Within the last two or three years the attention of the agricultural world has been directed to the importance of the correlation of the chemical and physical properties of soils with the crops and systems of agriculture which farmers have found most suitable to them.