CONTINUING EDUCATION UNITS (CEU) FOR CERTIFIED CROP ADVISORS

This article explores the issues of applying calcium and the various products on the market. Calcium is not an easy nutrient. Indeed, it has taken some time to earn its place as an important nutrient. Going back in history, it used to be seen as a problem owing to its association with calcareous soils and leaf yellowing. Things have moved on, but to understand calcium you need to know its antagonistic relationship with other cations, and what this means for fertilizer programs. This ‘problem nutrient’ is also rather needy, and is most effective when accompanied by boron.

This article offers the reader an introduction into boron as the enigma of micronutrients. Its range between deficiency and toxicity is narrower than that of any other mineral nutrient. More than 90 per cent of plant boron exists in its cell walls, where it plays major structural and physiological roles. Other central functions take place in cell membranes during cell division and elongation. Appropriate boron nutrition shows remarkable benefits for the grower in terms of yield increase and of maintenance of typical produce appearance, and may be needed where there is ‘hidden boron hunger’. The largest areas of boron-deficient soils are found in India, Korea, Nepal, Philippines, Thailand, Malawi, Nigeria, Sierra Leone and Zambia.

This article looks at Iodine deficiency as a problem for humans, affecting as many as 1 billion people in the world, and has been countered so far through iodized table salt. Agricultural practices can provide a solution through a process known as biofortification, which involves the incorporation of potassium iodide or potassium iodate into NPK fertilizers (along with zinc) or foliar applications alongside potassium nitrate. Results from trials on various crops are presented in this paper, showing this technique could be used on field crops and in greenhouses.

In many parts of the world, sugar cane is rain fed, but irrigation is growing strongly as farmers discover the advantages in productivity, efficiency and labour that localised irrigation offers. Pivot irrigation of sugar cane is an irrigation technique growing in popularity, and it allows for variable rate fertigation (VRF). Brazil has 1.5 million ha irrigated with pivots, of which nearly 10% are sugarcane.

This article looks at one of the fastest growing sectors for crop nutrition – water-soluble fertilizers. It looks at the benefits over granule fertilizers, and the requirements for water-soluble fertilizers when used in drip irrigation systems. The article looks at the key straight fertilizers that are used in water-soluble formulations. It then looks at the drivers for water-soluble fertilizers highlighting the countries that have the largest so-called protected cropping areas.

This article offers the reader an introduction into zinc as an important nutrient for human health, and an introduction to zinc sulphate, the main source of zinc used in agriculture. Many of the world’s soils are naturally deficient in zinc and the incorporation in zinc in plant nutrition provides an opportunity for biofortification, which increases the availability of a micronutrient in a crop for ingestion by human populations. An example is selenium-containing fertilizers that were used to increase the amount of selenium in wheat.