Grain sorghum can be grown on many different soils.
Sorghum will yield best on deep, fertile, well-drained loamy soils. However, it is quite tolerant of shallow soil and droughty conditions.
Sorghum can be grown successfully on clay, clay loam, or sandy loam soils.
Fertile, well-drained soils are important to optimize yield. Soils with clay loam or loam texture, having good water retention capacity are best suited for sorghum cultivation.
Grain sorghum is more tolerant of wet soils than most grain crops.
Sorghum grown on deep, well drained permeable soils usually develops extensive root systems.
Mature plant roots may penetrate to depths of 4 to 6 feet in an ideal soil.
Root development can be severely restricted by soil conditions such as excessively high or low soil moisture levels, hard pan and compaction.
Sorghum has moderate salt tolerance - slightly less than wheat but higher than maize.
It does well in pH range of 6.0-8.5 as it tolerates considerable salinity and alkalinity.
Sorghum is sensitive to aluminum toxicity and soils with acid saturation higher than 20% can pose a problem.
Striga infected sorghum fieldSoils seriously infected with witch weed or striga must be avoided.
In tropical and subtropical conditions of India, sorghum is extensively grown in light - textured red sandy,
red loamy, alluvial and coastal - alluvial soils as well as on mixed black and red and medium black soils.
Sorghum is also grown on medium black soils, deep alluvial loams and on sandy and gravelly soils of poor fertility with low organic matter content but the yields are low.
Climatic Requirements for Sorghum:
Sorghum can grow in a wide range of ecological conditions and can still yield well even under unfavorable conditions of drought stress and high temperatures.
Red dots indicate sorghum growing environment It is generally grown between 40oNorth and 40o South of the equator, in warm and hot countries characteristic of the semi-arid environment.
Sorghum requires warm conditions but it can be grown under a wide range of conditions.
It is also widely grown in temperate regions and at altitudes of up to 2300 m in the tropics.
It can tolerate high temperature throughout its life cycle better than any other crop.
Sorghum requires about 26-30oC temperature for good growth. The minimum temperature for the germination of the sorghum seed is 7 to 10oC.
Grain sorghum does not germinate and grow well under cool soil conditions. Poor emergence
and seedling growth may result if planted before soil temperatures reach 35oC. Sorghum is best adapted to areas having an average annual rainfall between 45 to 65 cm (17 to 25 inches).
Although sorghum can respond to good moisture supplies, it is nevertheless one of the toughest, drought
tolerant crops available and this tends to maintain its popularity in the regions where the weather is very unpredictable.
The ability of sorghum to grow in drier environments is due to a number of physiological and morphological characteristics;
- Produces many roots compared to other cereals,
- Has reduced leaf area thus reducing water loss through transpiration,
- Can remain dormant during drought and resume growth when conditions are favorable,
- Above ground parts of plant grow only after the root system is well established,
- The leaves have a waxy coating and have the ability to roll in during drought thus effectively reducing transpiration,
- Competes favorably with most weeds.
Field Preperation for Sorghum Cultivation:
The objectives of field preparation are based on the following principles:
- Elimination and control of undesirable plants like crop volunteers and weeds to reduce competition with the established main crop;
- Provide favorable conditions for sowing, allowing germination, emergence and good plant development;
- Maintenance of fertility and productivity over the long term by preserving the soil organic matter and avoiding erosion;
- Breaking of hard pans or compacted layers to increase water infiltration through the soil whilst avoiding erosion;
- Facilitating mixing of fertilizers, lime, or agro-chemical products into the soil;
- Incorporation of organic and agricultural residues.
Timely field preparation facilitates timely sowing which ensures higher yield. Land preparation should ensure that all crop residues, crop volunteers and weeds are completely buried.Summer ploughing is advantageous to kill the weed seeds and hibernating insects and disease organisms by exposing them to the heat of summer. Initial ploughing should be carried out at optimum moisture range to get good tilth and should avoid when moisture is in excess.
Number and depth of ploughings depends on weed intensity. For rainy season crop, with onset of rains in May-June, the field is ploughed once or twice to obtain a good tilth. Harrowing of soil should invariably followed after each ploughing to reduce the clod size. After the initial ploughing, the subsequent ploughings and harrowings are carried out
when the moisture content of the clods are reduced.The number of ploughings are to be minimized to reduce the cost of cultivation.
Tillage operations should be repeated when the weed seeds are just germinated. When the soils are heavily infested with perennial weeds like Cynodon or Cyperus, deep ploughing is needed.
Moisture is a critical element in good seedbed preparation and is essential for the successful establishment of the crop.
Field preparation depends on the system of sorghum sowing.
Three systems of sorghum sowing are followed:
1.sowing on a flat surface, or
2.using ridge-and-furrow system, or
3.on a broad bed-and-furrow system.
Chain attached to a wooden frame of a plough to level the land If sowing is done on a flat surface, the land should be leveled after final ploughing using bullock-drawn or tractor-drawn levelers.
In ridge and furrow system,ridges are made using either tractor drawn or animal drawn ridge ploughs.
Tractor drawn Ridger Ridge and Furrows
Animal Drawn Wooden Ridge Plough Animal Drawn Iron Ridge Plough
Animal drawn ridgers
Broad beds and furrows are prepared by an animal-
drawn ridger , mounted on a tool carrier (e.g., Tropicultor or Agribar), or by tractor-drawn implements with ridgers.
Making broad-bed and furrows with Agribar
Two ridgers may be fastened on a tool bar so that the top of the bed is 1.2 m wide and the distance from
the center of one furrow to the center of the next furrow is 1.5 m.
The depth of furrows should be 15 cm or more.
After forming the broad bed and furrows, the top of the beds are smoothened and leveled using a chain attached to a wooden frame of a plough or wooden-frame leveler mounted on
to a tool bar.
The broadbed-and-furrow system has many advantages over flat sowing. They are:
- helps in draining off excess water in the field and soil;
- provides more soil aeration for plant growth;
- greater in-situ moisture conservation;
- easier for weeding and mechanical harvesting.