Extracted leaf protein is now used regularly as human food in several places. For preliminary, or domestic, trials the equipment used is inconveniently large. A miniature extraction unit, which does not depend on electricity, is described.

The results are reported of three field experiments conducted from 1955 to 1963 to investigate the effects of sunn green manuring in the sugar cane rotation. In a three-year rotation with sugar cane and wheat, green manuring twice was not superior to green manuring once, either in terms of sugar cane yield or the nitrogen and organic carbon status of the soil. Two experiments showed that the yield increase of cane was proportional to the weight of the green manure crop, irrespective of how the latter was disposed of, suggesting that the only factor with which yield increase was correlated was the weight of roots of sunn which were incorporated into the soil. The green manure effect is resolved into two components namely ‘green matter effect’ and ‘legume effect’, both of which are additive and nearly equal.

This paper offers guidelines for the presentation of statistical material in scientific journals and project reports. Emphasis is given to the importance of planning a study so that the various components of statistical material can be linked to ensure the full efficiency of the work; if this is done well, the presentation of the results of the study, including the statistical components, can be achieved with greater ease.

Regional population recommendations for sorghum production in Botswana were calculated by applying long-term meteorological records to an experimentally developed model linking sorghum yield to plant population and rainfall. The basic recommendation at any place was taken to be that population maximizing local long-term yield means while keeping the risk of crop failure to one year in ten or less. Values ranged from 25 000 to nearly 70 000 plants ha−1, according to rainfall amount and reliability. The modifications of these basic recommendations necessary to allow for differences in standards of husbandry and for sorghum variety are discussed.

In order to identify the effect of burrowing nematodes on the shoots (pseudostem and leaves) of banana plants and to determine whether or not shoot characteristics are associated with plant resistance to nematodes two experiments were conducted in controlled conditions within polytunnels. The banana plants were harvested on three occasions for the measurement of root morphology and biomass. Varieties differed in their resistance to nematodes from resistant (Yg Km5, FHIA 17, FHIA 03) and partly resistant (FHIA 01, FHIA 25) to not resistant (FHIA 23, Williams). Nematodes reduced total plant dry weight at the first harvest in Experiment 1 and by an average of 8.8% in Experiment 2, but did not affect leaf area in either experiment. The ratio of above-ground weight to total plant weight was reduced from 75% to 72% in nematode-infected plants compared with the control plants for all varieties tested in Experiment 1, but was only reduced in FHIA 25 and FHIA 23 in Experiment 2. Varieties differed in above-ground growth. The FHIA varieties had greater shoot weights and leaf area than YgKm5 and Williams. Overall, resistance to nematodes was associated with the partitioning of a greater proportion of biomass to the roots than to above-ground parts

When agricultural experimenters send data to a statistics unit for analysis, they do not usually include a field plan of the experimental site unless specially requested to do so. But such a plan can be a great help to a biometrician: he can use it to check that the design used in the field was correctly described, and to arrange the plot residuals in the field layout as a way of detecting a fertility trend in the site and of relating anomalous values to particular locations on the ground. This paper gives examples of how a field plan can be used to the benefit of the experimenter.

Experiments in two successive seasons showed that planting date and spacing of bulbs affected the seed yield of Sudanese onions, but not the number of branches and seed heads produced by bulbs. Yield per plant increased with increase in spacing, but closer spacing gave the highest yield per unit area. Later sowing depressed seed size, weight and yield.

Differences in the water and air regime of the germination environment may cause variations of 30% and over in the yield of barley, wheat and oats.

In a second stock-scion trial with mango in Israel the influence of five rootstocks was investigated. In our first trial, two rootstocks—Sabre and 14·12—had been found suitable and unsuitable respectively. In the second trial, 14·6 and 14·7 were found to be not significantly different from Sabre, 3·2 was found to be somewhat inferior and 14·12 was again unsuitable. The important characters of the 22 varieties grown are described, and an evaluation is attempted of their yield and marketability.

The effects on local cucumbers of supplementary mineral fertilizers over an initial field dressing of 30 tonnes of poultry manure and 4 tonnes of lime/ha, were determined on tropical peat soil in Brunei. Significant yield increases were obtained with supplementary N up to 280 kg/ha but not with K/Mg above the basal rates 78/10 kg/ha. The highest yields exceeded 50 tonnes/ha of marketable fruit, obtained over a 9-week growing period.

An experiment to investigate the effect of planting pattern, time of planting the cowpea, and insecticide application on the yield of intercropped cotton and cowpea showed that insecticide applied to the cotton controlled cowpea pests best when the crops were planted in alternating single rows. I n wet seasons, delayed planting of the cowpea reduced its yield but its performance was better in alternating single rows than in other planting patterns. In drier seasons, cowpea yield was unaffected by time of planting and yields were similar with alternating single or double rows. Cotton yield was reduced by 47% when the planting pattern was changed to a one cotton:two cowpea row configuration.

The canopy light extinction coefficient (k) is defined as the exponential decline in the amount of light passing through the leaf layers as a function of leaf area index (LAI). This definition is standard in oil palm breeding trials and models of canopy photosynthesis, where k is sometimes assumed to have a fixed value. The present experiment aims to validate the alleged constancy of k. Therefore, k was inferred from the fractional transmission of photosynthetically active radiation (PAR) and LAI, as obtained from dura x pisifera test crosses of Nigeria and Ghana pisifera origins. The palms were planted at two densities (135 and 160 palms ha−1) in North Sumatra in 2010. At the age of 7.5 years after planting, the area of newly opened leaves approached a maximum. Transmission of PAR remained very low and was only weakly related to k. By contrast, LAI exerted a strong negative effect on k, which generated, under both densities, considerable differences in k between both origins and among pisifera within an origin. The assumption of applying a fixed k value for a certain genotype or palm density, as obtained during leaf expansion at closed canopy, may therefore not be realistic. The present study suggests that the relationship of k with LAI over time merits further investigation, starting just before canopy closure.

This study was designed to explore changes in soil bulk density (BD), soil organic carbon (SOC) content, SOC stocks, and soil labile organic carbon (C) fractions after 5 years of soil tillage management under the double-cropping rice system in southern of China. The experiment included four soil tillage treatments: rotary tillage with all crop residues removed as a control (RTO); conventional tillage with crop residues incorporation (CT); rotary tillage with crop residues incorporation (RT); and no-tillage with crop residues retention. Our results revealed that soil tillage combined with crop residue incorporation (CT and RT) significantly decreased BD at 0–20 cm soil layer compared to RTO treatment. SOC content and stocks were increased with the application of crop residues. Compared with RTO treatment, SOC content and stocks were increased by 16.8% and 9.8% in CT treatment, respectively. Soil non-labile C content and proportion of labile C were increased due to crop residue incorporation. Compared with RTO treatment, soil proportion of C mineralisation (Cmin), permanganate oxidisable C (KMnO4), particulate organic C (POC), and microbial biomass C (MBC) was increased by 196.1%, 41.4%, 31.4%, and 17.1% under CT treatment, respectively. These results were confirmed by the carbon management index, which was significantly increased under soil tillage with crop residue incorporation. Here, we demonstrated that soil tillage and crop residue incorporation can increase the pool of stable C at surface soil layer while increasing labile C content and proportion. In conclusion, conventional or rotary tillage combined with crop residue incorporation is a soil management able to improve nutrient cycling and soil quality in paddy fields in southern China.