Cropping Systems

Crop Rotation

Sorghum is an excellent crop to use in rotation with other crops, particularly cotton and soybeans. Using sorghum in a rotation with these broadleaf crops breaks up disease, insect and weed life cycles prevalent in these crops. Research shows typically higher cotton and soybean yields when following sorghum. Weed resistance is becoming a major issue in cotton and soybeans. Planting sorghum in rotation with these crops allows for the use of alternative crop protection products for control of these resistant weeds.  

The last few years have shown a major shift in tillage practices in the southern great plains. Producers are finding value in no-tillage and reduced tillage systems that reduce soil erosion, improve soil health, and greatly enhance rainfall capture in the soil.

Growth and Development

The first step in successfully producing a profitable sorghum crop is understanding how the plant grows and how the environment can impact its health. Key management decisions are tied to specific growth stages of the sorghum plant. 

Once the sorghum plant has emerged from the soil, it's growth can be divided into three general periods, these are referred to as growth stages one, two and three. Each growth stage lasts approximately 30-35 days depending on the environment. The first growth stage is characterized by vegetative growth and lasts from emergence to when the reproductive structures of the panicle or grain head begin to form in the stalk of the plant. The reproductive stage, the second growth stage, lasts until the panicle emerges at the top of the plant and it begins to flower. Flowering is the start of the grain fill stage, the final growth, and lasts until dry matter accumulation has ended within the grain.

A more precise model divides the growth and development of sorghum into 10 distinct growth stages.

sorghum growth stages

Numbered Stage

Descriptive Stage

Stage 0

Emergence - The plant breaks through the soil surface. Time between planting and emergence depends on soil temperature, residue cover and distribution, soil moisture, planting depth and seed vigor. Time planting so emergence occurs in favorable conditions.

Stage 1

Three-leaf - Only leaves with a visible collar. The growing point is under the soil surface, any damage to leaf area will delay flowering. Occurs 10-20 days after emergence, depending on soil temperature and moisture.

Stage 2

Five-leaf - Five leaves are fully expanded. The growing point is below the soil surface. The plant begins a rapid growth and nutrient accumulation. The root system rapidly expands. Minimize weed competition from planting through this stage. Occurs 20-25 days after emergence.

Stage 3

Growing point differentiation - Potential lead number is defined 30-40 days after emergence. Maximum plant growth and nutrient uptake rates are achieved. Head begins to form.

Stage 4

Flag leaf visible - rapid stem elongation and increases in leaf area. The final leaf, the flag leaf, forms. Potassium uptake is >40%, nitrogen >30%, phosphorus >20%, and total growth is 20% complete.

Stage 5

Boot - Maximum leaf area achieved. Maximum potential head size and seed number set. The upper stalk begins to elongate. Final size of the peduncle varies with the genotype. Occurs 50-60 days after emergence.

Stage 6

Half bloom or flowering - Full ecertion of head occurs and 50% of the plants in the field are in some stage of bloom. For an individual plant, flowering reaches halfway down the head. Total growth is 50% complete. Nutrient accumulation is 60% phosphorus, 70% nitrogen and >80% potassium.

Stage 7

Soft dough - Grain formation begins immediately after flowering and grain fills rapidly. The stem looses weight due to remobolization process. The head and grain are the main priority for plant.

Stage 8

Hard dough - Grain reaches 75% of its final dry weight and nutrient uptake is almost complete. Lower leaves lost functionality due to remobilization of nutrients to the grain.

Stage 9

Physiological maturity - Grain achieves its maximum dry weight. Growth is identified by looking for dark spot on the bottom of the kernel. Grain moisture ranges from 25-35%. The time to harvest depends on the environmental conditions.

Source: Louisiana State University Research & Extension

For pictures and a brief description of each stage, see link.