Management of Soil: 4 Ways

This article throws light upon the four ways used for the management of soil. The ways are:- 1. Cover Crops 2. Organic Amendments 3. Tillage 4. Crop Rotation.

Way # 1. Cover Crops:

Cover crops provide a canopy for seasonal soil protection and improvement between the productions of the main crops. Cover crops usually are grown for less than one year. When ploughed under and incorporated into the soil for improved fertility, cover crops are also referred to as green manure.

Cover crops have the potential for recycling nutrients which otherwise would be lost through leaching during off-season periods. Cover crops with shallow fibrous root systems, such as many grasses, rapidly build soil aggregation in the surface layer. Cover crops with deep roots can help break-up compacted layers, and bring nutrients from deeper soil layers to make them available for the following cash crop.

Leguminous cover crops can also fix atmospheric nitrogen for the benefit of the crop that follows. Other benefits from COYCr crops include protection of the soil from water and wind erosion, improved soil tilth and suppressing soil-borne pathogens.

Dead cover crop material may be left on the soil surface, and are then referred to as mulch, which can reduce evaporation of soil moisture, increase infiltration of rainfall, increase soil organic matter and aid in the control of annual weeds.

Leguminous cover crops suitable for the Northeastern US include clovers, hairy vetch, field peas, alfalfa, and soybean while popular non-leguminous cover crops include rye, oats, wheat, oilseed radish, Sudan grass, and buckwheat.

When selecting cover crops it is important to consider:

i. What are your goals for using a cover crop(s)? Is it to increase organic matter, break­up surface or subsurface compaction, weed and disease suppression, nutrient management, or prevent erosion?

ii. Where can cover crops fit into the rotation? Summer, winter, or season-long?

iii. When and how should the cover crop be killed or incorporated? Winter-kill vs. chemical applications vs. rolled and chopped?

iv. What cover crops are suitable for the climate?

v. What cover crops fit with the current production practices including any equipment constraints?

vi. Susceptibility or host status of the cover crop to major pathogen(s) of concern

Winter Cover Crops:

Winter cover crops are planted in late summer into fall, typically following harvest of a cash crop. Both hardy grasses and leguminous crops can be planted. Some crops like buckwheat and oats will be damaged by frost or winter-killed while others will require tillage, rolling or chemical management in spring prior to planting.

Although in Northern climates the choices are limited by the short can provide protection from soil erosion, suppression of weeds and root pathogens and can increase soil organic matter and aggregation. For late harvested crops, winter cover crops might be better inter seeded. Winter cover crops commonly planted in the Northeast include winter rye, hairy vetch, oats, wheat, red clover and various mixtures of the above.

Summer Fallow Cover Crops:

Summer fallow cover crops are more common in vegetable than field crop rotations. A fast growing cover crop could be planted between summer vegetable crops. However, this option is severely limited in the north by the short growing season and severe cold.

For example, buckwheat can be grown after early spring lettuce and prior to planting a crop of fall broccoli. In shorter season climates, a more successful option may be to inter seed a cover crop into the main crop once the latter becomes established, but it is important to avoid competition by the cover crop for water and nutrients.

Season-Long Cover Crops:

Full season-long cover crops, serve as rotational crops and are an excellent way of accumulating a lot of plant biomass. However, often this means taking the field out of cash crop production for a season. This will especially benefit fields with low fertility and farms with limited access to manures and other sources of organic amendments.

Relay cover cropping is also another option. This when a crop such as red clover is spring seeded into wheat, which then continues to grow after the wheat crop is harvested. It is important to keep in mind that some cover crops such as buckwheat, ryegrass, crown vetch and hairy vetch have the potential to become a weed problem if they set seed.

Way # 2. Organic Amendments:

Organic matter is critical for maintaining soil structure, and increasing water infiltration as well as water holding capacity. It can also increase cation exchange capacity (CEC), nutrient retention, and microbial diversity and activities. Organic matter can be added through incorporation of cover crops as green manures as well as additions of composts, animal manures and crop residues.

The addition of organic amendments is particularly important in vegetable production where minimal crop residue is returned to the soil and more intensive tillage is required that promotes the rapid depletion of soil organic matter. The impact of various organic amendments on soil physical, chemical and biological properties can be different and thus is important to consider when making soil management decisions.

Animal Manure:

The application of manure can have many soil and crop health benefits such as increasing nutrient levels (nitrogen, phosphorus, and potassium in particular) that benefit not only the crop but also the soil microbial community. However not all manures are created equal and will vary depending on the animal, feed, bedding, and manure-storage practices employed.

Manure containing a lot of bedding is typically applied as a solid while manure with minimal bedding is applied as a liquid. Manure solids and liquids may be separated, or can also be composted prior to application to help stabilize and nutrients. Due to the variability in nutrient content, manure analysis may be beneficial and take the guesswork out of estimating the nutrient content and characteristics of the manure.

Manuring of the soil can also influence soil organic matter and fresh un-composted manure is very effective at increasing soil aggregation. However, the impact is dependent of the amount of solids delivered, it also can increase the CEC, soil pH, and total pore space.

Careful attention should be paid to the timing of application and optimizing application to meet the needs of the crop or cropping sequence. Excessive or untimely application can cause plant or soil damage and pose an environmental danger to water resources.

Compost:

Unlike manure, compost is very stable and not a readily available source of nutrients. The composting process uses heat and microbial activity to quickly decompose simple compounds like sugars and proteins, leaving behind more stable complex compounds such as lignins and humic acids.

The stable products of composting are an important source of organic matter. The addition of compost increases available water capacity by improving water retention and pore space on which water and nutrients can bind.

Compost is less effective at building soil aggregation than fresh manure, because the readily-degradable organic compounds have already been decomposed. Composts differ in their efficiency to suppress various crop pests, although they can sometimes be quite effective.

Green manure crops:

Green manure crops are those grown for the purpose of improving the soil fertility with microbial diversity and organic matter content in general as opposed to cover crops which are grown more for the purpose of erosion protection and cycling of nutrients. When incorporated, green manures add a lot of fresh, readily degradable material to the soil, which fuels the soil’s microbial community.

The increased production of microbial exudates helps hold the individual soil particles together as soil with better aggregation (aggregate stability) is more resilient in heavy rain storms and is capable of greater water infiltration. In reduced tillage systems, one way to get the added benefits of green manure crops is to only incorporate them in the planting row and use the killed crop between the rows as a mulch.

Crop Residue:

Crop residue is another important source of organic matter. As it decomposes, the organic matter is going back into the soil and improving soil tilth. Crop residue left on the surface will protect against erosion and improve surface aggregation, thereby reducing crusting and surface compaction.

However, diseased crop debris can harbor inoculum that can become a problem during the next season if a susceptible crop is planted.

Crop rotation with non-host crops belonging to different plant families will reduce pathogen inoculum. Removal and composting of crop debris may be an option in some situations. Incorporation or plowing down of crop debris to encourage the decomposition process may be an option depending on the tillage system and crop rotation sequence being employed.

Other Sources of Organic Amendments:

i. Municipal wastes (yard debris, bio-solids)

ii. Organic wasted from food processing industries

iii. Organic wasted from paper mills, timber industry and brewing facilities

iv. Post-consumer food wasted (home, restaurant, and institutional)

Way # 3. Tillage:

As new technologies have been developed, the reliance on tillage to kill weeks, incorporate crop debris, and prepare seed-bees has been diminished. Extensive tillage reduces soil aggregation, resulting in crusting and soil compaction as well as often stimulating the microbial community that burns off organic matter quickly.

There is consensus that reducing tillage intensity will improve soil health and over time reduce production costs.

There are many different strategies for reducing tillage intensity aside from going to no- till. Strip tillage uses a shank set at the depth of the compacted layer (if present) to rip the compacted layer and then a series of coulters to form a narrow, shallow ridge into which the seeds are planted.

Zone tillage is similar to strip tillage without the rip shank. Instead of preparing the entire field as a seedbed, only a narrow band is loosened, enabling crop or cover crop residue to remain on the soil surface as a mulch. Implementing the use of permanent drive rows often better facilitates reduced tillage systems.

Reduced tillage can also be thought of in the long-term and modified based on the cropping sequence. Different tillage practices can be rotated depending on the soil management goals and concerns.

For some crops such as potato, more intensive tillage and soil disturbance may be required in order to establish and harvest the crop, but the subsequent sweet corn (or other) crop(s) could be strip-or-no-tilled into a killed winter rye cover crop.

However, the type and timing of tillage is often site specific and dependent on the cropping system and equipment availability. Reducing both tillage frequency and intensity will reduce the burning of organic matter and lead to improved soil tilth and microbial activity, resulting in soils that are less susceptible to compaction and more resilient.

Way # 4. Crop Rotation:

Initially, crop rotation was practiced as a way to avoid depleting the soil of various nutrients. Today, crop rotation is also an important component of soil and pest management in many agricultural production systems. Crop rotations can be as simple as rotating between two crops and planting sequences in alternate years or they can be more complex and involve numerous crops over several years.

Proper crop rotation can reduce insects and disease- causing pathogens as well as weed pressure by breaking their lifecycles through removal of a suitable host. Crop rotation can also aid in nutrient management through incorporation of crop residues and improve soil resiliency after a root crop such a carrot or potato.

Many growers find yield increases when crops in different families are grown in rotation versus in monoculture and this is often referred to as the “rotation effect”.

One basic rule of crop rotation is that a crop should not follow itself. Continuous cropping will result in the build-up of disease causing pathogens, nematodes, insects and weeds that can lead to yield reductions and the need for increased inputs such as herbicides, insecticides and other pesticides.

The development of a cropping sequence should take into consideration the use of cover crops and season-long soil building crops for improving soil tilth and increasing soil organic matter.

Rotating with a diversity of root structures from taproots to fibrous-rooted crops will also improve the soil’s physical, chemical and biological qualities. However, developing successful crop rotation sequences is farm specific and dependent on the unique combination of location and climatic factors, as well as economic and resource limitations.