This archive report was first published on 23 November 2019.
Soil fertility is a critical aspect of agriculture, and understanding the importance of soil pH and nutrient balance is essential for achieving optimal crop growth.
Soils lose most of their nutrients through various means, including overcultivation, erosion, and burning of farm waste. In some cases, nutrients are leached beyond the plant's root zone or washed away by running water and deposited in water catchment areas.
The use of salty water for irrigation can make soil nutrients unavailable to plants due to high or low soil pH levels. Therefore, farmers must manage the pH levels of their water and soil to create a slightly acidic environment for optimal crop growth.
However, the availability of nutrients in the soil does not guarantee that plants will absorb them. Plant nutrient uptake is affected by various factors, including soil moisture content, soil temperature, soil pH, and physical soil conditions such as compaction.
Presence of one nutrient in the soil can prevent the uptake of another, a phenomenon known as antagonism. To achieve good yields, farmers must ensure that the soil provides an optimal environment for crops.
There are 14 nutrients required by plants for growth, which are broadly classified as macro and micro nutrients. Macronutrients, such as nitrogen, phosphorus, and potassium, are needed in large quantities, while micronutrients are required in small amounts.
For optimal growth, farmers must maintain a balance between micro and macro nutrients. Imbalance can lead to deficiencies, toxicities, or interference of one nutrient with the absorption of others, causing crop stress and decreased quality and yield.
Soil test analysis is critical for determining the right fertilizer programme. Many farmers conduct soil tests, but interpreting the results can be challenging. A farmer who applied less fertilizer than recommended due to misinterpretation of soil test results lost his crops.
For example, if a soil test shows high pH levels, low nitrogen, and low phosphorus, the farmer should use DAP during planting and incorporate it into the topsoil about 20cm depth. During top dressing, Ammonium Sulphate should be applied in two splits, at day 30 and 45.
