Theme 04: Soil Fertility and Plant Nutrition
Description
Micronutrients, also known as trace minerals, which chiefly include boron (B), molybdenum (Mo), copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe), are required in extremely small quantities by crops and livestock. Their name, however, is not meant to imply their role is minor. Their lack, e.g., can cause serious crop production problems in forages and health disorders in livestock. This presentation includes the response of forage legumes and grasses to micronutrients, their deficiency and sufficiency levels in forages and their sufficiency levels in livestock. Forage legumes are more responsive to micronutrients, particularly B and Mo, than grasses. There are fewer documented cases of Cu, Fe, Mn and Zn deficiencies than of B and Mo deficiencies in forages. Soil acidity is one of the primary factors affecting the availability of micronutrients to forages. Low soil pH, e.g., is the principal cause of Mo deficiency in soybeans in Brazil and in a variety of crops in eastern Canada. More often soil properties and environmental factors are more important than actual soil levels, in affecting micronutrient availability. Micronutrient deficiencies have been emerging as a major problem in intensively cultivated soils in many countries and have become one of the serious constraints to crop productivity. Deficiency symptoms for most micronutrients appear on the young leaves at the top of the plant, because most of these nutrients are not readily translocated. However, Mo is an exception in that it is readily translocated, and its deficiency symptoms generally appear on the whole plant. Toxicity symptoms, on the other hand, for most micronutrients appear on the older leaves of the plant which is very striking, e.g., for B. Soil, foliar and seed applied methods of micronutrient application to control their deficiency are discussed in detail. Frequently the Cu, Fe, Mn, Zn and Se levels in forages which are sufficient for optimum crop yields are not adequate to meet the needs of livestock. Selenium is a trace mineral which is not required by plants and maximum forage yields can be obtained on soils with very low amounts of soil Se. However, if animals are fed forage with low Se, they could suffer from serious muscular disorders and other diseases. White muscle disease caused due to Se deficiency is the most common disorder and is found in calves and lambs. Sufficiency levels of micronutrients for crops have been discussed in relation to the animal requirement.
Included in
Micronutrients in Grassland Production
Micronutrients, also known as trace minerals, which chiefly include boron (B), molybdenum (Mo), copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe), are required in extremely small quantities by crops and livestock. Their name, however, is not meant to imply their role is minor. Their lack, e.g., can cause serious crop production problems in forages and health disorders in livestock. This presentation includes the response of forage legumes and grasses to micronutrients, their deficiency and sufficiency levels in forages and their sufficiency levels in livestock. Forage legumes are more responsive to micronutrients, particularly B and Mo, than grasses. There are fewer documented cases of Cu, Fe, Mn and Zn deficiencies than of B and Mo deficiencies in forages. Soil acidity is one of the primary factors affecting the availability of micronutrients to forages. Low soil pH, e.g., is the principal cause of Mo deficiency in soybeans in Brazil and in a variety of crops in eastern Canada. More often soil properties and environmental factors are more important than actual soil levels, in affecting micronutrient availability. Micronutrient deficiencies have been emerging as a major problem in intensively cultivated soils in many countries and have become one of the serious constraints to crop productivity. Deficiency symptoms for most micronutrients appear on the young leaves at the top of the plant, because most of these nutrients are not readily translocated. However, Mo is an exception in that it is readily translocated, and its deficiency symptoms generally appear on the whole plant. Toxicity symptoms, on the other hand, for most micronutrients appear on the older leaves of the plant which is very striking, e.g., for B. Soil, foliar and seed applied methods of micronutrient application to control their deficiency are discussed in detail. Frequently the Cu, Fe, Mn, Zn and Se levels in forages which are sufficient for optimum crop yields are not adequate to meet the needs of livestock. Selenium is a trace mineral which is not required by plants and maximum forage yields can be obtained on soils with very low amounts of soil Se. However, if animals are fed forage with low Se, they could suffer from serious muscular disorders and other diseases. White muscle disease caused due to Se deficiency is the most common disorder and is found in calves and lambs. Sufficiency levels of micronutrients for crops have been discussed in relation to the animal requirement.
