In general, there are two methods of planting crops: direct seeding and transplanting. Direct seeding is either by broadcast, hill or dibble, or by drill method. The hill and the drill methods are alternative options in row planting.
Direct seeding or direct sowing is a method of planting in which seeds are directly planted on the ground in the farm or any growing surface while transplanting makes use of pre-grown plants, seedlings or vegetatively propagated clones. The term transplanting is also used to refer to the practice of replanting an already established plant in one location and moving it elsewhere.
Direct seeding generally applies to large-seeded vegetables as well as in cereals and grain legumes. Transplanting is most common with small-seeded vegetables, vegetatively propagated crops, ornamental crops, fruit trees and many perennial crops. The term direct seeding is also commonly used to refer to the planting of seedpieces or underground vegetative planting materials directly into the soil.
Planting crops by broadcasting or sabog tanim, or scatter planting, commonly applies to small seeds, like rice and mungbean, that are capable of germination and sustained growth without soil cover. There is no control of plant-to-plant spacing. The seeds are simply distributed on a well prepared ground by hand or with a mechanical broadcaster.
With hand broadcasting, a volume of seeds is held by the hand and thrown with a wide swath. Skill is important to ensure even distribution of seeds per unit ground area based on the desired seeding rate per hectare. For example, a seeding rate of 100 kg per hectare means that the seeds have to be distributed at an average of 0.01 kg or 10 g per sq meter. Assuming that the crop is rice with a weight of 1000 grains of 29 grams, this is equivalent to a seeding rate of about 345 seeds per sq meter.
Excessive seeding per unit area will mean that the prepared seeds will have been completely sown but a portion of the farm is still unplanted, and so additional seeds need to be procured. Conversely, seeding below the average will complete the planting of the entire farm with some seeds still left.
In lowland rice, the seeds are broadcasted on puddled soil or over water and allowed to germinate without covering. The broadcast method of planting crops is also common with mungbean and cowpea grown as green manure. But in upland farming, it is best to pass a tooth harrow or rake after broadcasting to cover the seeds. The soil covering will hide the seeds from seed-harvesting organisms like chicken and birds. It will also ensure that the seeds have full contact with the soil which will maximize germination and improve the chance of the seedlings to fully develop. In pasture establishment, a large herd of livestock can be released after broadcasting to press the seeds into the ground by their hooves.
Dibbling is an old method of planting crops practiced by subsistence farmers in hilly lands. My late grandfather used to do this on a portion of the farm in Sarangani. That part of the farm, now grown to coconut that is regularly harvested for copra, has a very steep slope with shrubs, stumps of trees, and large limestone. Plowing by carabao was impossible so that the only way to prepare the land was by slash-and-burn or kaingin system.
Slashing and burning are done during summer when the grasses are dry, and corn is planted at the start of the rainy season. With a dibbler or “panghasok” (a pointed, spear-like stem) held by one hand, he strikes the ground to make holes about 2 inches ( 5 cm) deep and 1-2 steps apart. As the pointed tip of the dibbler is lifted, someone else immediately drops 3-4 seeds of an indigenous, open-pollinated corn into the hole. The hole is not refilled with soil, that part is done naturally by the cascading downward movement of surface soil and fragments of rock. Between harvesting and burning, the area is fallowed.
In both the hill and drill methods of planting crops by direct seeding, there is a desired row-to-row spacing. Hills with a single or multiple number of plants are spaced uniformly within each row so that in the hill method there is always a reference to hill distance and number of plants per hill. A hill is that specific spot on the ground on which a plant or a group of plants is grown. In contrast, there is no uniform spacing between plants in the row in the drill method, but uniformity in number of plants per linear meter is intended.
The hill method of direct seeding is done by dropping seeds in holes made by a dibbler or in furrows that are more or less equidistant. But with mechanized farming, a combine furrower-planter is commonly used.
In planting corn under rainfed conditions at a population density of, for instance, 60,000 plants per hectare at 1 plant per hill in rows 70 cm apart, the farmer walks forward along a furrow and drops a seed every 23.8 cm to the bottom of the furrow. He does not carry a measuring tool, he just estimates distances on the ground with impressive accuracy borne of long experience. To cover the seeds, he merely sweeps the ridge at either side of the furrow by one foot to push some soil toward the seed and steps thereon to press the soil on top of the seed.
The drill method of planting crops is done, either manually or mechanically, by releasing seeds continuously, as if pouring water from a bottle with a small opening. Manual drilling applies to small seeds like rice, millet, and mungbean and is usually done by hand. It can also be accomplished by placing small, roundish seeds in a bottle with a hole on the cover. The seeds are simply released by tilting and slightly shaking the bottle so that the seeds drop one after the other or in a cascade through the hole and toward the ground.
The seeds are drilled with or without furrows. In rice, drilling in puddled soil in linear direction is a modification of seed broadcasting in which plants are dispersed without plant-to-plant spacing. But in rainfed sorghum, mungbean, and other grain legumes, the seeds are always drilled at the bottom of the furrow, covered with soil by raking or by foot, and stepped on to press the soil.
Just like in the hill method of planting crops, an even distribution of drilled seeds is intended but varies with the seeding rate per hectare and row distance. With a seeding rate of 100 kg per hectare in rows 20 cm apart, the calculated average seeding rate per linear meter in the row is 2 grams. With 1000 grain weight of 29 grams for rice, this is equivalent to a seeding rate of about 70 seeds per linear meter. But if the row distance is widened to 25 cm, the average seeding rate will increase to 2.5 grams or 86-87 seeds per linear meter.
In contrast to direct seeding, transplanting is a method of planting crops in which potted plants or pre-grown seedlings or clones are planted on the ground, other growing surface, or any growing structure. Transplanting is also convenient with a few plants that can be transferred with a ball of soil around the roots. In some vegetables, it is common to prick seedlings from the seedbed and transplant them bareroot to the garden plot. In perennial species like coffee at a time when rainfall has become frequent and light is not intense, uprooted wildlings or bareroot transplants have been directly planted.
(Ben G. Bareja March 2011)