Soil structure is very influential in the field of agriculture. Soil as a growing medium for plants be decisive how the harvest will be obtained. If the structure is too stable it would be hard to penetrate the roots, otherwise if the stability of the structure is too weak then the availability of nutrients and water will be slightly because the land can not bind nutrients and water with strong, therefore it takes a balanced soil structure.
In soil with good structure, sand and dust particles are held together in aggregates (small clumps) by clay humus and calcium. A large empty space between aggregates (macropores) forming the circulation of water and air, as well as the plant roots to grow down to the ground deeper. While the small empty space (micropores) hold the water for plant needs. Ideally, that the so-called granular structure.
Figure 1:31. Macro and micro pores in the soil
Soil structure has direct influence on the growth of the plant, where the structure of soil crusts (light) generally results partum rate-harbor plants and the production per unit time higher than the structure of solid ground. The number and length of the roots of plants growing in soil crusts are generally more than the roots of plants growing on soil structure weight.
This is due to the development of roots in the soil of structured light / crumb faster per unit time compared to the plant roots in the soil compact, as a result of easy interception at the root of every pore of the land that is available on the ground a lot of crumbs. Besides the roots have a chance to breathe optimally on porous soil, than on solid ground. Conversely for forage crops grown in soil finely textured like argillaceous ground, it is difficult to develop roots because it is difficult for the roots to spread due to low soil pores.
Plant roots will have difficulty penetrating dense soil structure, so that the roots do not develop properly. Activity of plant roots and soil organisms is one of the main factors forming soil aggregates. Based on the above texture reflects the particle size of fractions of soil, the structure is the appearance of the form or structure of primary particles soil (sand, silt and clay) to secondary particles which is a combination of primary particles called blobs (ped) to form aggregates (lumps) ,
Soil particles are not joined, especially textured sand without structure or structures called off, while the textured clay soil that looks solid without pore space is soft when wet and hard when dry or when crushed with water to form a paste called also without structure. Soil structure influences function to modify the texture of the condition of drainage or soil aeration, because of the arrangement between ped or soil aggregate will produce a larger space than the arrangement between primary particles.
Therefore, well-structured soil will have good drainage and aeration conditions are good also, and further facilitate the entry of plant root system to absorb nutrients and water, so that growth and crop production would be better. It is evident from fertilization experiment which found that the production of corn in the soil without fertilizer but beragregat well turned out 2.3 times greater than production in poor soil beragregat fertilizers. Planting protect the soil aggregates from the force of the rain, so the tighter the plant canopy will be better influence on soil aggregates.