The productivity of agricultural land is an economic concept that is determined by three factors, namely: (1) land management system, (2) results (of production), and (3) the type of soil. The value of agricultural land is highly dependent on the value of land productivity, more productive, then the higher the value of agricultural land. In the management of farmland there are two aspects to consider, namely:
(1) Capacity (carrying capacity) of land. Each soils cultivated by a certain type of plant has the ability to accept one or several inputs such as fertilizer and water in order to produce and generate maximum profit.
(2) The capacity of the plant. Each type of crops grown on the soil type also has a certain ability to receive one or several inputs in order to produce that yield maximum profit.
If the capacity of the plants in each planting season is directly dependent on the ability of genetic and environmental factors, the role of these two factors is relatively constant, so that the input required is also relatively fixed. However, the capacity of the soil although influenced by both of these factors, only at the beginning of its use are determined at the genetic capability. The ability of this genetic decline with increasing duration of use, so that productivity will depend on the input is added, so that the land becomes unproductive if no input input.
Even the genetic ability to produce this ground will quickly drop drastically if utilization is done without proper management. The bearing capacity of the soil to produce is determined by:
- The content of soil mineral material. Mineral soil naturally membe-liberated nutrients into the soil solution slowly, so it will not be able to offset the nutrient needs of plants are driven in order to produce maximum.
- Levels of organic matter. Speed to the breakdown of soil organic matter in order to liberate nutrients become available to plants have varying speeds depending on the type of organic compounds. The organic material in the form of carbohydrates is the fastest to the slowest and decompose lignin.
Umumya supply of nutrients from the mineral material is relatively slower than the organic material. This means that the land is a natural resource which has a carrying capacity is limited, so the assumption that the crops are grown done only with menugalkan seed or immerse seeds without fertilization or the addition of nutrients can no longer tolerable if it wants to have a productive land ,
Utilization of land in accordance with its carrying capacity, means that the absorption of some nutrients available in the soil by the plant are not counted in the total, but gradually in accordance with the level of availability and balance with other elements. By the law of minimum Liebig productivity will be achieved in a country will be determined by a factor whose existence minimum, so if the plant to produce optimum is only determined by the availability of at least 16 nutrients essential, and the availability of the minimum of the 16 elements is what will be limiting production to be achieved.
To meet the concept of nutrient availability and balance, then during each preparation of planting, fertilizer and soil improvement should always be done in accordance with the results of soil analysis (both the chemical properties, physical properties and biological) and recommendations.