Pakistan is an agricultural country. The overall land area of Pakistan is about 76.9 million hectares. In Pakistan about 27% area is under cultivation. Out of this 27% cultivable land 76% is irrigated area and rest is fall into arid area. In arid areas the crop production is totally depend upon the rainfall. The rainfall in the arid areas is changing from the less than 100mm to more than 1000mm with the average rainfall of 400mm. If the farmer receives the rain at the proper time, the farmer can get the good stand of the crops. Farmer can obtain about 24% of the rape and mustard seed, 27% of the maize, 52% of the barley yield, 56% of the sorghum, 77% of the gram, 83% of the ground nut, 84% of the pulses and about 90% of the gaur seed if rainfall is appropriate and at proper time. But due to the climatic change and reckless rainfall pattern, a significant amount to the yield is lost in many previous years even the unreliable rainfall caused the total crop failure in some cases. This unreliable rainfall causes the water scarcity and drought conditions. So, the crop production become risky is arid areas due to water scarcity and drought. This ultimately causes the heat stress in the plants. The one of the easiest way to compensate this problem is the use of the mineral or nutrient which forced the crop to grow better under the drought conditions and increases the ability of the crop against the heat stress. One of such mineral is the silicon.
Silicon a mineral
Silicon is the 2nd most abundant mineral present in the earth crust. It contributes about 27.7 percent of the total soil weight after the oxygen. It present almost 450g in per kg of the sandy soils and about 200 to 300 g in per kg of the clay soil. Most of the plants absorb the silicon in almost equal amount of the macronutrient. But the problem is that silicon which is present in the soil is in unavailable polymerized form and plants can only absorb the silicon when it is converted in to the depolymerized form by any chemical or biological reaction in the soil. Monosilicic acid which is also called orthosilicic acid [H4SiO4] or Si (OH4) is the available form of the silicon to the plants.
- Sources of the silicon fertilizer:
There are different sources through which silicon can be obtained such as inorganic industrial wastes e.g. Coal fly ash, steel slag, wollastonite, bauxite-processing mud etc. can be used as fertilizer source furthermore calcium silicate, potassium silicate, sodium silicate, quartz sand (fine grind) and amorphous silica can also be used to augment soil silicon.
- Role of silicon:
Silicon increases the drought tolerance ability of plant by regulating the water balance, erectness of the leaves, photosynthetic efficiency and structure of xylem vessels under the moisture stress, high temperature and high transpiration.
Silicon also alleviates the physical stress such as drought, radiations, high temperature and UV. Silicon can also alleviate the chemical stress like metal toxicity, nutrient imbalance and salts etc. Silicon accumulates in to the cell walls of the xylem vessels which prevent the vascular compression under high transpiration which is caused by the heat stress or drought. Silicon improves the photosynthetic activity and increases the enzymatic activity under water deficiency.
Intensive land use (without the proper nutrient management) has depleted a significant amount of the silicon from the soil and according to the FAO estimate, almost 210-224 million tons of silicon is removed from the soil so it is the need of time to give awareness to the farmers about the importance of the proper management of nutrients like silicon furthermore in arid areas where drought and water scarcity are the major problems, silicon can be used as a fertilizer for improving the crop performance under such crucial conditions so that maximum yield can be obtain.