Please have a look at an interesting review , i just got and thought to share with you all...

Natural recovery of soil physical properties from treading damage of pastoral soils in New Zealand and Australia: A review,https://doi.org/10.1016/j.agee.2005.11.028Get rights and content

Abstract: This paper reviews natural recovery of deteriorated soil physical condition under animal treading in grazed pastoral systems, particularly in New Zealand and Australia. While much research has focused on soil compaction and physical deterioration from animal treading, there has been much less focus on natural recovery of soil physical properties after treading damage has occurred. Natural recovery of deteriorated soil physical condition improves soil properties including hydraulic conductivity, macropore volume and bulk density. Soil physical condition naturally recovers when animals are partially or completely excluded from pasture, although improvements are likely to be limited to no deeper than 10–15 cm soil depth, under common grazing practice or animal exclusion. However, the physical deterioration and natural recovery processes are linked in a cycle. Natural recovery of soil physical condition in this cycle is therefore important when evaluating management practices affecting soil deterioration on-farm, field trial interpretation, and ungrazed riparian zone soil structure. This review also discusses directions of future research to enhance soil management, including quantifying and evaluating soil physical deterioration and natural recovery. Several knowledge gaps relating to pastoral agriculture in New Zealand and Australia, particularly under rotational grazing management on intensive dairy farms are discussed. Further research is required into the consequences of farm management practices that enhance natural rejuvenation of degraded soils. Consequently, integration of both deterioration and natural recovery of soil physical condition in the soil compaction and recovery cycle is needed to improve farm system evaluation and management. Natural recovery of soil condition when animals are partially or fully excluded from grazing is therefore important in management and modelling of pastoral and ungrazed riparian soil, and subsequent environmental impacts.

Lets concentrate the debate on degraded soils , not degraded environment..then there will not be any limit...

Its very difficult to fix up a time limit for degradation of soil to take place since two basic classes of triggering factors, anthropogenic and non-anthropogenic origin are involved. Magnitude and intensity of these factors using a variety of forecasting models have been suggested

I have heard it said in my past training, that it takes about 100 years to build an inch of topsoil. I have also seen substantial soil improvement in gully stabilization work when severely eroded areas were reshaped, ripped if needed, fertilized, mulched, planted to various grasses, forest, etc. Although considered an invasive plant by many, Sericea lespedeza was used in some of our early gully stabilization work, can fix a substantial amount of nitrogen, and helped produce a stand of 10 -14 Inch plus dbh loblolly pine trees in a decade. I was also impressed with how fast a smoothed over gullied area developed organic layer when fertilized, mulched and planted to switchgrass in the grass mix. I was impressed with the density of organics produced in just one to two years by the switchgrass.

But at the other extreme, I have also viewed gullied and barren lands (sometimes called galls) from past farming erosion, that apparently are so damaged, lost all A and B horizon, exposing saprolite, so even after many decades, there is little or no sign of natural restoration. Some soils, in recovery needed to be fertilized more than once, so vegetation would be healthy.

Soil scientists would be good to consult as they test soils and offer or prescribe suggestions on reference conditions, current status and options on recovery (level, rate, cost, etc.). .

All physio chemical properties of the soil

To begin, it fundamentally depends on both (1) the previous state, your target and (2) the current degraded state.

It may not be possible to obtain an identical soil.

However, if the degradation is reversible, it is potentially possible to restore the health of a given soil.

The question is then, how much time, money and effort is necessary to meet the target.

If your only target is soil organic matter, that makes the work easier as we know what to aim for.

Nevertheless, I would argue that your affirmation that "agriculture disturb the soil" is partially correct.

Depending on the practices, agriculture can be a soil-building activity.

A forest soil, rich in organic matter, turned into a field will certainly see a massive decrease in its organic matter content. But the use is not the same.

In an agricultural field managed with a care for biological fertility, you could observe a very healthy and active soil, providing food and other services to the people and the environment.

Agriculture can destroy but it can also build healthy soils.

Have you tried scanning through the Organic Agriculture Standard like that of IFOAM or if you have your own country's Organic Standard? Issues in rehabilitation and consideration if the farming area has in a way regained its fertile or safe for farming state are discussed. It could be one good reference to start your job.

It would also be desirable if we try to first know the main cause of degradation.

I truly believe that the entire science community is missing a very important factor about soil and farming, irrigation, etc. You cannot make the soil fertile or safe for farming forever. There are airborne contaminants which constantly travel around the world spreading contamination and viruses through our jet streams which have recently changed within the last few years. This has been happening since the industrial revolution and has never stopped and isn't going to. Soil amendment is a rotating door. We have exhausted our farmlands, contaminated our soil, and water. Change in temperatures affect the biodiversity on the planet, this in turn depletes the microorganisms which in turn affects everything! The world must change their method of growing food or we will meet our demise in more ways than one. Scientists have big egos and sometimes they hate to be wrong, but I say this for the benefit of everyone, not everyone will die in a nuclear war, those that survive will have no food, no water, and no power, etc. Forget that you have a phd. It will do us no good if we continue to follow what we've been taught and others who will be wrong! No solutions can be found if we're all stuck on the same theory. Nothing is the same anymore, therefore we cannot base our science on the text that is presently available. If you think you are going to amend the soil and make good again, good luck! But you might want to check out countries which have no food and why?

Interesting point Esteban . Fertility of a soil is a complex dynamic property . This property of the soil cannot be made like a static property. Why a soil becomes degraded from production point of view , and when we talk from the angle of raising a crop successfully , it becomes a doubly difficult task to transform a fertility depleted soil to a fertile soil. Lets debate from this angle so that soil degradation could be dealt more precisely....

In response to your first question, plants deplete soil from nutrients because soil does not produce nutrients on it's own, rather nutrients are broadcasted to soil through water mixed with decay, replacing the nutrients plants will need to survive in soil. You can grow plants in water with nutrients, however, you cannot grow anything in soil without water, (excluding moisture as well). In response to your second question, biodiversity as we all know is not common in every place on the planet and is the essence of micros and the food chain all the way up to mankind. The amendment of soil is very simple so as long it is allowed to develop itself rather than having humans induce it and making something happen instead of allowing it to happen. That is our problem, we try to force everything because of the demand and end up destroying it more than it already was. I will continue as I must leave now. Thank you.

In addition, when we run an aquaponic system we integrate biodiversity through a man-made marsh, compost, vermiculture, and just about everything you find in nature including bees. By staying away from high end technology we stay closer to Mother Nature. In this process we create organic soil rich in nutrients without chemicals or destroying the environment. However, no matter how much you amend it, man will contaminate it again. We must stop doing what we have done for decades if we are to help the planet and mankind survive.

Esteban , we cannot afford to use to organic sources of nutrients so indiscriminately , unless soils are really degraded to the extent , they need to be ameliorated to regain their lost crop productivity potential...We also must consider the availability such resources , however alternative uses could be to raise green manures for recuperation of degraded soils. Green manuring very often seems like forgotten practice of the past. ..

I agree with you and that's why I am saying that if we can produce organic soil amendment indoors in a greenhouse, it can better serve to amend nutrient depleted soil and the cost is zero because most of what helps produce organic soil is all around us down to the waste of foods and other biodegradable materials such as leaves from trees, weeds, dead bugs, etc. If we induce chemicals we change the natural process Mother Nature uses to add nutrients to soil. You must also take into consideration that the temperatures on the planet are getting hotter. Photosynthesis stops at 104, when temperatures get hotter than that, plants have a difficult time with the chemical transition known as the "Carbon Dioxide Fertilization Effect." So it's not just soil, it's everything to do with biodiversity and how it can be applied to degraded soils.

Please have a look at an interesting review , i just got and thought to share with you all...

Natural recovery of soil physical properties from treading damage of pastoral soils in New Zealand and Australia: A review,https://doi.org/10.1016/j.agee.2005.11.028Get rights and content

Abstract: This paper reviews natural recovery of deteriorated soil physical condition under animal treading in grazed pastoral systems, particularly in New Zealand and Australia. While much research has focused on soil compaction and physical deterioration from animal treading, there has been much less focus on natural recovery of soil physical properties after treading damage has occurred. Natural recovery of deteriorated soil physical condition improves soil properties including hydraulic conductivity, macropore volume and bulk density. Soil physical condition naturally recovers when animals are partially or completely excluded from pasture, although improvements are likely to be limited to no deeper than 10–15 cm soil depth, under common grazing practice or animal exclusion. However, the physical deterioration and natural recovery processes are linked in a cycle. Natural recovery of soil physical condition in this cycle is therefore important when evaluating management practices affecting soil deterioration on-farm, field trial interpretation, and ungrazed riparian zone soil structure. This review also discusses directions of future research to enhance soil management, including quantifying and evaluating soil physical deterioration and natural recovery. Several knowledge gaps relating to pastoral agriculture in New Zealand and Australia, particularly under rotational grazing management on intensive dairy farms are discussed. Further research is required into the consequences of farm management practices that enhance natural rejuvenation of degraded soils. Consequently, integration of both deterioration and natural recovery of soil physical condition in the soil compaction and recovery cycle is needed to improve farm system evaluation and management. Natural recovery of soil condition when animals are partially or fully excluded from grazing is therefore important in management and modelling of pastoral and ungrazed riparian soil, and subsequent environmental impacts.

Lets concentrate the debate on degraded soils , not degraded environment..then there will not be any limit...

Lots of valuable inputs are already given. Based on our experience in working in small watershed projects, three years was the time generally required for soil restoration normally.

I agree with Prof. Anoop

It is basically a function of conservation measures and applying them appropriately. Land treatment always gives the best results, and if done well, the investments on structures on the drainage line is reduced.

Its difficult, but you can start by doing biological activity analysis and microbial quantification in order to have data that could help you to determine your soil’s organic matter degradation capacity. That would be one of a hundred things you should analyze.

Most important issue is , how a practitioner will come to know , his soil has started displaying signs of degradation , especially in terms of soil fertility depletion...

Maintenance and enhancement of the quality of degraded soil are, in essence, dependent upon the improvement of physical, chemical and biological properties of the soil.

Whilst Farmers are on the front lines in many ways they are often at the bottom of the food-chain when it comes to being able to make a positive difference without going broke.

How can Farmers make a difference? Well, it takes a village. That village includes: Bankers, financiers, City, village, county, borrough, government, farmers, city planners, ecologists, conservationists, water experts, engineers, dieticians, chemists, sales, stores etc. Etc. Often the bulk of the responsibility will fall on the land-leading farmer - sadly.

To understand the history and background of which modern farming developed, as well as the many challenges farming has please go to: Agriculture industry facts, information, pictures for so much more.

Whilst it may be easy to dismiss the importance of dirt, it's a fact that soil is vital to humankind. Stop soil erosion by finding ways to conserve soil. There are several methods of soil conservation that can be achieved through agricultural practices and measures you utilise at home.

The Food and Agriculture Organization of the United Nations (FAO) finds soil and water conservation (SWC) go hand-in-hand and describes and defines it as activities "which maintain or enhance the productive capacity of the land in areas affected by or prone to degradation."

Soil degradation is the process in which soil loses the functions that deliver services and goods that plants, animals and people depend on. Degradation can result from depletion of nutrients and organic matter, soil compaction, loss of soil structure, lack of proper drainage, and an increase in salinity or acidity.

Soil conservation should address these problems as they can have local and global consequences.

Improve Soil Productivity

FAO says one important reason to conserve soil is to maintain and improve local farm production of food and guarantee livelihoods. Current practices in farming and livestock management unfortunately are themselves the main causes of soil erosion and must be addressed to make soil productive again.

Conventional cultivation methods involving tillage destroys the structure of the soil. For example, Brazil losses 55 million tons of topsoil each year due to agriculture, according to World Wildlife Fund (WWF).

In addition, industrial farming which relies on heavy application of chemical fertilizers, herbicides and pesticides destroys many beneficial soil microbes, and insects responsible for fertility. Continuous use of chemical fertilizers renders soil barren, and 10 million hectares of farm per year get abandoned due to degradation according to WWF.

Pastoralism is an important source of income in all parts of the world. However, overstocking and overgrazing lead to trampling and removal of vegetation cover that destroys the structure of soil degrading and exposing it to erosion, so these areas can no longer support livestock.

Ecosystem Services

Besides food, soils provide many other regulating services such as carbon sequestration, waste treatment by soil microbes, and moderating extreme events like floods, according to The Economics of Ecosystems and Biodiversity (TEEB). "Fertile soils are a non-renewable resource" in human lifespans as they take thousands of years to be formed points out a 2015 scientific assessment. Globally 30% of the land surface is affected by soil erosion, and costs 300 billion US dollars each year. 46% of this cost is borne by the owners or managers locally, however 54% is a loss to the global community in terms of public goods such as carbon sequestration.

Aims of Soil Conservation

Soil conservation seeks to restore the lost services that land provides under natural conditions. On-site, which is where erosion occurs, conservation brings about beneficial changes to soil fertility, purifies water and air, prevents floods and fights climate change. Conservation is important to address disturbances caused in places where the soil is deposited off-site, like reduction of polluted runoff and eutrophication.

Agriculture Soil Conservation

Three ways to conserve soil through agricultural means include:

1. Practice no till farming. With no till farming, crops are allowed to remain rather than being plowed under at the end of the season. This practice keeps soils anchored in place rather than having bare ground exposed to wind and water.

2. Use terrace farming. This type of farming uses the topography of the land to slow water flow through a series of terraces. This manipulation of the water flow prevents it from gathering speed and washing soil away from farmlands.

3. Practice contour farming. Contour farming replicates the effects of terrace farming, but on a smaller scale. Rather than planting crops in straight vertical rows, crops are planted following the contour of the landscape. Crops planted up and down hillsides create pathways for water to flow. Crops planted parallel to the land slow the flow of water that prevents soil erosion.

· Terrace farming for hilly areas, to prevent water from gathering force on its way downhill and eroding soil. The terraces also hold water and can be absorbed by the soil.

· Contour planting also slows water by creating paths across the slope and not along the slope.

· Biological means like no-till farming keep soil surface intact and reduce risk of erosion.

· Restoration of wetlands because they absorb rainwater and eroded soil.

· Watershed measures such as restoration of forest cover to prevent soil erosion by wind and water and also improve rainwater absorption by the soil by breaking the impact of rain and providing ideal humus rich soil conditions.

· Plant buffer strips of grass, shrubs and trees to prevent or reduce runoff into water-bodies.

· Reduce impervious surfaces like pathways where water cannot be absorbed.

· Harvest rainwater from the impervious surfaces with a ditch in the garden or from the roof in a barrel.

· Plant wind breaks in gardens or farms to prevent wind erosion.

Soil Fertility

Building topsoil lost in sheet, rill and gully erosion can lead to improved soil fertility, as nutrients are present in topsoils. This is the zone where microbes living in the soil recycle important elements in humus and release them for plant growth, claims the Centre for Ecology and Hydrology (CEH).

Purify Water and Air

These microbes would also help in breaking down toxic wastes and are an important method of natural soil remediation. Thus they keep pollutant levels down and water and air clean, according to TEEB.

Prevent Floods

By improving structure of the soil, its capacity to absorb and retain water is restored. Areas with compact or little soil would otherwise lead to increased runoff of rainwater, and therefore floods leading to stream and river bank erosion or flood plain erosion according to CEH.

Reduce Polluted Runoff

In industrial farms, there are residues of chemical fertilizers, pesticides and herbicides in soil which also get carried too during erosion. These are deposited in rivers and streams, contaminating drinking water per a study for the Dutch Soy Coalition commissioned by Friends of the Earth Netherlands and Cordaid, or turn rivers and streams turbid affecting its quality in Brazil. Soil conservation can contain soil locally or eliminate use of chemicals. This also has the added advantage of preventing loss in livelihoods due to declining fish catch in rivers polluted by agricultural chemicals in runoffs as reported from Brazil.