SynopsisWith 7 corn hybrids at various locations in Virginia, hybrids were more important than growing conditions as a source of variation in oil content; the reverse was true for the effect on protein content. With 3 levels of N, P, and K, and at 10,000 and 16,000 plants per acre, the location, planting rate, and N level all significantly affected protein content. Protein content was significantly higher under drought conditions than under good growing conditions. Highest protein yields occurred with the higher plant stand and heaviest N application. None of the factors had any appreciable effect on oil content:

Nitrogenous fertilizers—in some form—are applied to most lemon orchards and in the majority of cases constitute the only fertilizers used. The growing of legume or other cover crops for the most part has been abandoned.

A review of climatic conditions has been given to show the relationship between the distribution of rainfall and the production of wheat in the Callide Valley region. Data have been presented to show the total amounts and the percentage chances of receiving specific quantities of rainfall during the fallowing, planting and growing periods for wheat. Comments have been made on the selection of planting time and the suitability of varieties for grain and hay production. The influence of soil nitrogen supply and frosts upon wheat production in the Callide Valley has been discussed.

The native soil zinc that is equally as available to plants as is a standard source of zinc supplied as fertilizer, may be estimated from yield-of-zinc curves if the total zinc in the aerial portions of the plants is related to the available zinc supply in a soil, and the amount of available native soil zinc is unaffected by the addition of fertilizer zinc. A logarithmic relationship between zinc in the substrate and zinc in the aerial portions of plants was found when plants were grown in ion exchange resin-sand-nutrient cultures. From 88 to 95% of the variation was accounted for by the logarithmic regression equation. When plants were grown in soils, the yield-of-zinc curves obtained were also curvilinear and could be described by logarithmic or parabolic equations. The estimated available native soil zinc values found by solving the logarithmic regression equations were significantly correlated, r being +0.800, with the zinc contents of the control plants. On the other hand, available zinc by parabolic fit and dithizone extractable zinc were also significantly correlated, with a correlation coefficient of +0.847. In further experiments, the soil zinc values found from the yield-of-zinc curves obtained by growing millet, were less than those found from the yield-of-zinc curves obtained by growing oat and tomato plants.