Soil Fertility, Evaluation and Nutrient Management
Major contributors to increased agricultural production * Fertiliser use * Plant breeding * Other cultural practises * (planting date, crop density, rotations etc) * Weed and pest control * Irrigation
Future Challenges * World population continues to grow * Decrease in productive land due to industrial, residential, transport use and soil degradation * 2 degree increase in temperature over 100 years * Extreme weather conditions * Advances in agricultural production needed to feed population
Factors for crop yield * Plant growth and yield are affected by over 50 factors * We cannot control many of the climate factors * Soil and crop factors can be managed for maximum and economical production * Table: major factors affecting yield potential
The Law of the minimum * Crop yield is determined by the most limiting factor * Crop yield can only be increased by eliminating the most limiting factor * Yield cannot be increased by increasing the supply of other nutrients and factors * Challenge is to identify the limiting factors and eliminate them
Sources of mineral nutrients for plant uptake * Plants take up mineral nutrients from soil solution * Amounts of nutrients in solution are small * Soil solution nutrients are replenished by there in soil/solid form
Table: Nutrient dynamics in the soil that affect nutrient supply to plants
The intensity factor of nutrient supply is the nutrient concentration in soil solution
Quantity Factors * Is the amount of nutrient adsorbed on soil surfaces that can replenish the soil solution
Nutrient buffering capacity * Ability of a soil to re supply a nutrient to the soil
BC is described by the change in the amount of an ion adsorbed (∆Q) as a result of the change in soil