Crop density and geometry

• Plant density is the number of plants per unit area in a cropped field.
• It indicates the size of the area available for individual plant.
• Yield of a crop depends on the final plant density. The density depends on the germination percentage and the survival rate in the field.
• Establishment of required plant density is essential to get maximum yield.

(a) Plant Density and Yield

• Biological yield increases with increases in plant density up to a point and reaches a plateau with further increase in density, thus no additional biological yield can be obtained. On the other hand, the economic yield increases with increase in plant density up to a point and subsequently decreases with increased in density.

(b) Plant Density and Growth

• Plant height increase with increase in plant density due to competition for light. Dense plant stands leads to reduction in leaf thickness and alters leaf orientation. Dry matter production per unit area increase with increase in plant density up to a limit, as in biological yield

Crop geometry

• is the pattern of distribution of plant over the ground or the shape of the area
• available to the individual plant, in a crop field.
• It also refers to the shape of the space available for individual plants.
• It influences crop yield through its influence on light interception, rooting pattern and moisture extraction pattern.
• Crop geometry is altered by changing inter and intrarow spacing.

Planting pattern

Square planting; Square arrangements of plants will be more efficient in the utilization of light, water and nutrients available to the individual plants than in a rectangular arrangement.

Rectangular planting;

• Sowing the crop with seed drill, wider inter-row and closer intrarow and closer intra-row spacing leads to rectangularity.
• Rectangular arrangement facilitates easy intercultivation.
• Rectangular planting mainly suits annual crops, crops with closer spacing etc., the wider section (row) is given for irrigation, intercultural operation etc.
• This method accommodate high density planting. It can facilitate intercropping also.

Triangular planting  It is a method to accommodate plant density under perennial/tree crops.

Miscellaneous planting –

• In rice and ragi transplanting is done either in rows or at  random.
• Skipping of every alternate row is known as skip row planting. When one row is skipped the density is adjusted by decreasing inter-row spacing. When the inter row spacing is reduced between two rows and spacing between two such pair are increased then it is known as paired row planting. It is generally done to introduce an inter crop

AFTER CULTIVATION

It refers to the cultural operations like thinning, gap filling, harrowing, tilling and other operations carried out in a field after the crop has emerged. Thinning and gap filling are done to keep optimum density.

• Thinning is done to reduce higher density due to over seed rate or more seeds/hole and uneven broadcasting.

Gap filling is done to fill the gaps that exist due to 

• Poor quality seed,
• Soil crusting,
• very shallow or very deep placement of seeds, and
• Poor moisture availability in dry land.

Gap filling is done to maintain density by replacing with seedlings reserved for this purpose or resowing with seeds.

Gap filling is done reasonably early so that plants come to maturity along with other plants.Time may vary with duration of crops. For example, in sugarcane it may be done even 30 days after planting. But in short duration crops like maize, sorghum, rice etc., it should be done within about 10-15 days.