The analysis of radiation climate is a central problem of agricultural meteorology because rates of photosynthesis depend on the receipt of visible light and rates of transpiration depend on the net exchange of radiation by a crop canopy. Both short-wave (solar) and long-wave (terrestrial) radiation are correlated with cloud amount, and in south-east England the income of net radiation in summer is proportional to the income of solar radiation.

In principle, the fraction of total radiation in the visible waveband depends on cloud cover and on the amount of absorption and scattering in the atmosphere, but in practice the fraction is often between 0·40 and 0·45. The calculation of photosynthetic efficiency needs a figure for the number of quanta (or Einsteins) per unit energy, and this figure can be calculated from the mean wavelength of the radiation weighted by energy, about 0·55μ for direct sunlight.

The reflection of radiation by vegetation changes with solar elevation, and at angles between 40° and 60° it ranges between 0·15 for a rough crop (e.g. pineapple) to 0·26 for smoother crops (e.g. sugar beet, kale). The transmission of radiation through the canopy can be expressed as a function of the leaf area index and a parameter that depends on the distribution and orientation of leaves.

A two-year field experiment was conducted with fifteen varieties of cowpeas to evaluate responses to three different planting dates in relation to flowering and yield of beans. It appeared that most of the cowpea varieties required a day length of more than 12 hours to initiate flower formation. During both years 1962 and 1963, May plantings gave the best results, and July, August and September plantings failed to form flowers.

A factorial (3 × 3 × 3) experiment using three levels of nitrogen, phosphate and potassium was conducted to evaluate the effects of these elements on the formation of nodules. Results indicated that increasing levels of nitrogen depressed the formation of both effective and ineffective nodules, but phosphorus and potash did not produce any significant effects. Although the soils of the experimental plots were highly leached and strongly acid in nature, the native strains of rhizobia were able to produce copious amounts of effective nodules on plants growing on plots where no nitrogen was applied. It appeared that the naturally occurring rhizobia strains in these soils are well adapted to their natural environments.

An experiment was carried out in the glasshouse to determine the availability of P, and utilization of added phosphate fertilizers from three fertilizer materials, applied by two different methods to sugar cane grown in four diverse soil systems. Phosphorus was applied at the equivalent rate of 175 pounds P (400 pounds P2O5) per acre. A larger response from added P in terms of plant yields was obtained from an aluminous ferruginous latosol and least from dark magnesium clay. Differences in yields of sugar cane were evidently associated with differences in P content in the cane plants and, in certain cases, with a reduction in Al content in plant tops, and the less soluble superphosphate increased yields more than the highly soluble NH4H2PO4. Phosphate fertilizers applied as foliar spray greatly increased the P content in the plants, and plants contained twenty times more P when sprayed with NH4H2PO4 than when the same fertilizer was applied to the soil. However, increased P content in the plants did not necessarily indicate that the P was translocated within the plants or that the added P participated in metabolic processes. The evidence indicated that in soils where the ‘A’ value was high the P status of the sugar cane tops was not correspondingly high.

A perennial rye-subterranean clover pasture in Western Victoria, Australia, was fertilized at three levels of sulphate of ammonia and subjected to eight cutting treatments over four months in autumn–winter. The cutting treatments simulated deferment of grazing for different periods followed by fortnightly defoliation. Both nitrogen and cutting had significant effects on first cut and total yields for the period. There was interaction between nitrogen, cutting and first cut yield but not between nitrogen, cutting and total yield for the period. The results are used to argue that, in the year of the trial, deferred grazing was likely to have been profitable and nitrogen fertilization to have been unprofitable.

Yields are presented for a 54-week cutting experiment (1962–3) in which coastal bermuda (Cynodon dactylon sp.), pangola (Digitaria decumbens) and guinea (Panicum maximum) grasses were subjected to three cutting heights (1, 3 and 6 inches), four cutting intervals (1, 3, 6 and 9-weeks) and four nitrogen fertilizer regimes (0, 8, 16 and 32 cwt sulphate of ammonia per acre per annum). The results indicate that coastal bermuda and pangola grasses will tolerate severe cutting but not guinea grass. The highest dry matter yields were obtained from guinea grass, at 16½ tons/acre. Whereas the highest yields of coastal bermuda and pangola were 12½ and 12 tons/acre respecitvely. In the absence of measures of nutritive value it is impossible to say which is the best management system to adopt, but the facts presented may help to determine management practices.

A simple but reliable type of drainage lysimeter was used to measure evaporation rates from lucerne and wheat and these were compared with calculated estimates of evaporation. Plant height was found to have an important effect on the amount of water lost from a plant cover, which also varied between two different species of crop of similar heights. Using two different soil types, maintained at a high moisture status, the rate of water loss was not influenced by the type of soil in which the plants were grown.

The time and method of placement, and the distance from the plant at which fertilizers should be placed, was studied on sole-crop cowpeas. The development and yield of both early and late season crops were highest where fertilizers were applied at planting. It is suggested that it might be more advantageous to plough the fertilizers under before planting, so that the nutrients will become available to the seedlings from the time they emerge. Application of fertilizer in two bands gave the highest yields, but was not significantly superior to a less laborious method of application in one band. The distance at which the fertilizer was placed, and treatment interactions, did not show any definite trends.

As part of a project to introduce Virginian-type flue-cured tobacco varieties into a new area, a number of experiments on the effect of time of planting showed that returns declined according to the delay in planting after the start of the rains. This decline was not arrested by differential fertilization, soil fumigation or the use of quicker maturing varieties. The early plantings appeared to have a greater growth potential, which could often be more fully realised under improved cultural techniques. Thus, early plantings gave substantial positive responses to applications of nitrogen which had little effect on, or were detrimental to, later plantings. It is suggested that the responses noted were linked with weather conditions during the first few weeks after planting. The drier and more sunny these were, the better, and the possibility therefore arises of using rainfall probability data, with a minimum of field experimentation, in future problems of this nature.

Suggested rules are given for the presentation of numerical data in a scientific agricultural journal. These are that all tables of numerical results should be sufficiently clear to render unnecessary any reference to the accompanying text; and that treatment means (and other statistics) should always be accompanied by their standard errors, rather than by least significant differences or by asterisks showing the results of significance texts. Examples are given of correct and incorrect presentation of results, and the graphical presentation of results is also discussed.