The invention provides a composition in concentrated form (“the concentrate”) for dilution with water in the preparation of an agricultural composition for application to crops, soil or animals, comprising a carbohydrate-based pH modifying agent and a pH indicator. The agricultural composition comprises an agricultural chemical whose agricultural activity varies with the pH of the water. The proportions of the pH indicator and the pH modifying agent in the concentrate are selected so that when the concentrate is diluted with an appropriate amount of water, the pH indicator indicates visually by coloration of the composition, whether or not the pH of the water is suitable for acceptable agricultural activity of the chemical. The invention also provides a process for preparing the agricultural composition by mixing the concentrate with water, and adding the agricultural chemical to the composition, if it is not already present in the concentrate.