Endorsing an excellent response from Paul, while examining the aggregate stability , we need to look proportion of soil coagulating cations like Ca and Mg iver Na and K.Indices like residual sodium carbonate , exchangeable sodium percentage and sodium adsorption ration can also throw some significant light on extent of aggregate stability in relation to type of salts.

Our issue is how to improve aggregate size and organic matter content of the soil. Number of practices like green maturing as cover crops, maturing using conventionally used bulky matures, mixed cropping instead of monocropping, use of legumes in cropping sequence, multiple inoculation using a variety of microbes including mycorrhizal, ...but the bigger question is , how to retain the addition of organic carbon for successive crops to be grown..? It is also an issue , how to divert the affed organic carbon to passive pool and regulate soil fertility requirements via active SOC fraction..?

The stimulation of soil aggregation and promotion of water aggregate stability are key indicators of soil improvement. Burning will lower soil organic matter and reduce soil structure by decreasing soil organic matter. Zero tillage as well as not burning bush are both critically important practices as well as amendment of organic matter especially to low organic matter soil to increase soil aggregation and aggregate stability. Particularly improve is the strategic use of compost. The soil can be favorably influenced when acid by the use of liming with the calcium carbonate which works to help soil aggregation and its stabilization. When clay and organic matter are bonded together with lime the aggregates are of increased durability compared to naked organic residues and manures. This not only improves soil structure and chemistry but also works to counteract against global climate change through taking carbon out of the atmosphere and stabilizing it in the soil. Sandy soils can be inhibited by low insufficient clay to help stabilize the soil aggregation. In an arid sandy situation, the use of trench composting which contains some clay and silt is useful in developing soil organic matter of longer effect. Liming acid soils use of reduced and zero tillage permanent forage cover reduced burning and compost production and utilization are factors which can greatly increase soil structure. Water and air are chief limitations to root growth and health the action of stabilized soil organic matter address both lack of water and the need for optimized aeration being useful in both sandy and clay soils. 

Dear Dr. Peter, Best one is the CA practices,

Thanks  

In the attached the photo you will see that the aggregation of the soil is a function of the soil organic matter content. Soils in virgin conditions had superior of 5% soil organic representing an optimized condition. All the practices which lead to that improved soil organic contents will give results in better soil structure and conditions. 

In Burkina Faso, our study show that “stone rows” and “stone rows + planting (P. thonningii)” contributed significantly to improving soil total carbon content and soil aggregation

It show significant improvement soil total carbon and soil aggregation due to increase soil organic matter and minimum soil disturbance so the stone rows serve as barrier against wind and water flood while plant are not disturb so attain their maximum growth boost organic matter.

Zero tillage, conservation and organic agriculture may help. Beside this, organic binding agents like roots and hyphae  can help to stabilize micro-aggregation and crop rotation helps in   macro-aggregation.

Periodic addition of farm yard manures is a must.Inclusion of green manure crops at least once in two years shall have synergistic effect.Addition of legume crops having high biomass will be greatfully useful.Besides this agronomic practices such as conservative tillage and never leaving land without vegetation cover esp. during peak summer months and consequently irrigating with good quality water shall be boon.Vermiculture per se with reduced tillage operations also pays to improve the and stablize aggregation so that overall soil structure remains crumble,which is best for crop production as well as soil health.

Kulvir Singh, Manure is an important resource. For stability of soil aggregates the use of manure can be used to feed the soil aggregation process. Worms are the great soil engineers. When shade and water is provided the earthworms can process these crop and animal wastes stabilizing them and increasing their value. In addition the worm caste can be solubilized to stimulate the aggressive early establishment and growth needed for highly productive agriculture. It also can be employed at critical stages of crop development increasing the plant nutrition and allowing plants to adapt better.

Many soils are very sandy and this is a big constraint. The ability to improve soil organic matter is associated with both clay and calcium content. Neither clay nor calcium are globally scarce commodities. Calcium content is critical for liming acid soils and for allowing better aggregation in saline environments. The world resources of lime and gypsum are vast and need to allocated to balancing the soil reaction. Gypsum for saline environments and lime for acid environments.

The use of no till is very important as well as manuring but we need to pay attention to the constraints of soil compaction and mineral insufficiency. Just if not more important are crop and animal rotations.

These issues are helped when plant and animal production systems can be integrated into one seamless structure where the plants feed the animals and the animals feed the plants and both plants and animals feed the soil.

The disarticulation of our food system has been the result of using linear industrial models for agriculture rather than circular ones with each loop plant animal and soil builds upon the other.

Endorsing an excellent response from Paul, while examining the aggregate stability , we need to look proportion of soil coagulating cations like Ca and Mg iver Na and K.Indices like residual sodium carbonate , exchangeable sodium percentage and sodium adsorption ration can also throw some significant light on extent of aggregate stability in relation to type of salts.

Our issue is how to improve aggregate size and organic matter content of the soil. Number of practices like green maturing as cover crops, maturing using conventionally used bulky matures, mixed cropping instead of monocropping, use of legumes in cropping sequence, multiple inoculation using a variety of microbes including mycorrhizal, ...but the bigger question is , how to retain the addition of organic carbon for successive crops to be grown..? It is also an issue , how to divert the affed organic carbon to passive pool and regulate soil fertility requirements via active SOC fraction..?

Dear Sir, Green manures and cover crops plus crop rotations are fundamental. We need to do complete soil analysis and design our approaches around specific goals fro improving our soils.

I lie to start on what is going on in regards to soil pH. I believe most soils are either too acid or too alkaline to optimize results. In the alkaline soil situation you need to identify if the problem is mostly related to sodic character or alkalinity is the issue. Alkalinity with no salt issue can be mostly easily addressed using sulfur and ammoniated fertilizers to bring the soil pH to approach neutral 7.3 is usually sufficient. If sodium is the issue the use of gypsum is needed along with a leaching and look at how the watering is contributing to the issues.

Even in areas of limiting soil acidity there is usually resources of local lime which can be used for these constrained environments. If you take about one third of soils constrained by acidity and another significant proportion with alkalinity and soil issues this is a huge and largely not attended issue in our global food system. Many times our fertilization contributes to long term issues. A lot of applied work is needed I believe.

In old weathered soils so common in the tropics they have the largest ability to be transformed by remineralization. I believe the plant production of many of these environments are mineral starved and soil remineralization is critical to returning higher productivity rejuvenating the worn out resources. This is so important since these areas have good sun and water.

Throughout the world our chief limiting primary productivity is the ability to maintain and recycle our water supply. From the initiation Carbon is linked with water hydrated carbon the sweet elixir of life on the blue and green marble of earth. This is the reason focusing on Carbon is so important. A worthy side effect is the ability to counteract greenhouse gases by putting them back where they beyond in the rich dark earth.

Factoid at 1% or less of soil organic 100 soil units will be able to absorb and recycle less than 30 units of water. The same soil at over 5% soil organic matter can absorb and recycle more than 200 units of water a 6 times increase.

Some thoughts.

I think we discussed the chemical agencies related to aggregation more than the primary importance of biology. We talked a little about earthworms as great soil bioengineers. Much early work stressed bacteria and exocellular polysaccharides. Much more recent work is putting increasing emphasis on the role of mycorrhizal fungi especially the functioning of glycoprotein glomalin which coats the soil aggregate making them stick together and coveying water repellency which allows they not to disarticulated in presence of water. Modern agricultural practices have not given much attention to ability to detect critical levels and to promote their activities and populations. Cover crops are be quite effective in stimulating greatly increased mycorrhizal activity. Earthworms and mycorrhizae are great bioindicators of soil health.

Water stable organic matter has play a good role particularly from the standpoint of plant nutrition and the environment ( metal ion toxicities through chealation, acidifying effects on natural waters and carries of xenobiotics). Beside this, in most of the soils bulk of the soil organic matter occurs as stable humus. Beside this, litter pool is important in the cycling of nutrients in forest soils, natural grasslands. and crop production agriculture.

The water-stability of aggregates in many soils is shown to depend on organic materials. The organic binding agents have been classified into (a) transient, mainly polysaccharides, (b), temporary, roots and fungal hyphae, and (c) persistent, resistant aromatic components associated with polyvalent metal cations, and strongly sorbed polymers. The effectiveness of various binding agents at different stages in the structural organization of aggregates is described and forms the basis of a model which illustrates the architecture of an aggregate. Roots and hyphae stabilize macro-aggregates, defined as > 250 μm diameter; consequently, macroaggregation is controlled by soil management (i.e. crop rotations), as management influences the growth of plant roots, and the oxidation of organic carbon. The water-stability of micro-aggregates depends on the persistent organic binding agents and appears to be a characteristic of the soil, independent of management.

Please see a good paper on this aspect.

Use of ERM of AMs is one of the effective ways of improving water stable soil aggregates , in addition to improving organic matter content....