I believe in the black clay soils as in the Indian subcontinent and other parts of the world subsoil compaction is the most limiting issue.

Soil compaction

Quick facts Soil compaction concerns have been growing in Minnesota as both annual precipitation and farm equipment size have dramatically increased.Wet soils are particularly susceptible to compaction. Heavy equipment and tillage implements amplify damage to the soil's structure, decreasing pore space and limiting soil and water volume even further.Improving soil structure is the best defense against soil compaction. A well-structured soil holds and conducts the water, nutrients and air necessary for healthy plant root activity.What is compaction? Soil compaction occurs when soil particles are pressed together, reducing pore space between them (Figure 1). Heavily compacted soils contain few large pores, less total pore volume and, consequently, a greater density.A compacted soil has a reduced rate of both water infiltration and drainage. This happens because large pores more effectively move water downward through the soil than smaller pores.In addition, the exchange of gases slows down in compacted soils, causing an increase in the likelihood of aeration-related problems. Finally, while soil compaction increases soil strength – the ability of soil to resist being moved by an applied force – a compacted soil also means roots must exert greater force to penetrate the compacted layer.📷Figure 1: Effects of compaction on pore space.Soil compaction changes pore space size, distribution and soil strength. One way to quantify the change is by measuring the bulk density. As the pore space decreases within a soil, the bulk density increases. Soils with a higher percentage of clay and silt, which naturally have more pore space, have a lower bulk density than sandier soils.Myths about soil compaction There are two common, widespread myths about soil compaction:Freeze-thaw cycles will alleviate a majority of the soil compaction created by machinery. Whatever compaction Mother Nature doesn’t take care of, deep tillage or subsoiling will.

Suitable conservation measure along with converting lands into grasslands may be a solution.

Traction and walking on soil will compact it.

Tillage can cause the dreaded plow pan that restricts the rooting capacity.

No tillage is one of the options.

Compaction interferes with the percolation and does not allow water penetration and inhibits aeration.

In alkaline saline soils, the use of calcium as gypsum is needed along with leaching the excess sodium.

Sorghum sudangrass and oil radish are biological methods of penetrating compacted layers.

Cover crops and crop rotation are important for the clay soils which are easily deteriorated in their physical condition.

Mechanically the layers can be broken by a deep spike. This requires heavy duty horse power and equipment.

For a field system the use of soil adjustment can be combined with a permanent raised bed method and the water can be provided under a mulch by drip irrigation

Beside the use of gypsum the optimization of the organic matter and the ability to add sand can be critical. .

Using the same path of matching and transit greatly inhibits the impacts of the compaction.

In the bed the use of mulch and organic amendment can maintain a better soil conditions.

The physical condition of clay soil is greatly enhanced by optimized Calcium and pH and by focusing on organic matter the use of use of biochar can be wonderful in the acid clay soil and compost works pretty much in all soil conditions.

To optimize soils a chemical physical and biological analysis can all be helpful.

Oil seed radish is interesting biological tool as it both breaks the compacted layers but also fumigated the soils for pathogens insects and weeds.

It also is vegetable of value.

While Oil seed radish can adapt to fall plantings the sudangrass is excellent for the summer and tropical application.

While black clays which are vertisols are physically challenging they have potential to be highly fertile and productive when adaptive cultivation systems are employed.