Managing soil health with conservation tillage

As food demands and farming methods develop, more farmers are understanding that crop production requires balancing resources to maintain productivity over the years to come. One precious resource that can get overlooked is soil health.

Standard tilling and extensive use of heavy farm equipment underestimate how much of an effect it has on the healthy functioning of soils. Many farmers are starting to understand that the loss of healthy soil is the root of some of their problems.

This is why more and more are turning to conservation tillage to manage arable land. Conservation tillage is a farming practice that is favourable for the soil along with other practical benefits for the farmer. It’s also a practice that promotes carbon farming.

Tillage and soil health

For many farmers, ploughing the soil is a standard farming practice to get the planting started. That is, to begin the sowing process, a good home for seeds to germinate and for the roots to grow must be prepared. Typical seedbed preparation involves killing weeds, incorporating nutrients, and managing the stalks and roots from previous crops (residue). Tilling the soil achieves this for the farm.

Common tilling methods involve mixing, digging, and turning the soil surface. In this process, intact soil properties are broken up which affects its overall structure, removes nutrients, and disturbs the organic matter makeup of the soil. While a provisional remedy for this can be in the form of added nutrient inputs, soils depleted of fertile properties will take longer to recover and harder to manage.

Degraded soils have decreased capacities to withstand other natural disturbances such as wind and water that triggers soil erosion. This leads to more use of other heavy equipment which can lead to compacted soils that have reduced rates of water absorption, making irrigation and nutrient requirements more demanding.

Heavy ploughing also results in the loss of organic matter in the soil, decreasing the presence of beneficial microorganisms, nutrients, and the soil’s ability to store carbon. The carbon found in the soil indicates the fertility of the land which affects productivity and yield. Building back soil carbon is a long process that takes many years to incrementally recover.

What is conservation tillage?

Conservation tillage is a type of land management that is less intrusive to the soil than conventional farming. It’s all about protecting the topsoil by managing crop residue and limiting soil disturbance with minimum or no-tillage. It has also been defined as any tillage system that leaves at least 30% of residue on the soil surface.

Conservation tillage is used to enhance farm functions in four ways. This ranges to soil health, resource use, productivity, and soil carbon sequestration.

4 ways conservation tillage improves the farm

1. Promotes soil health

As a result of leaving residue near the surface of the soil, there is more organic matter content present in the soil that promotes soil quality, indicated by increased microbial activity.

The presence of residue in the soil also limits compaction, allowing better water retention and the release of nutrients for crop growth. Healthy soils that retain moisture have a better chance of withstanding strong winds and water that cause soil erosion.

2. Conserves resources

Soil that is not compacted has room for water to trickle down deeper and for nutrients to penetrate for plant uptake. As a result, runoff and nutrient leaching can be avoided. This is not an unusual issue for some farmers who rely heavily on fertilisers.

Soils that hold nutrients make their application more efficient which can decrease costs associated with purchasing more fertilisers and pesticides.

3. Decreased energy use

The poor state of farm soils could require more interventions using tools and equipment. Bigger farms also require more passes from machinery that require fuel to run and more hours to complete the task.

Intensive tillage with fuel-run machinery adds to costs and labour. The less the soil is tilled, the more energy is conserved related to the activity.

4. Carbon sequestration 

Tillage impacts carbon emissions and carbon sequestrations. Breaking up the soil releases its carbon and nitrogen content into the atmosphere, contributing to greenhouse gas emissions and soil nutrient loss.

Retaining crop residue in the field enhances the function of soil as carbon sinks induced by the accumulation of soil organic, especially when compared with nutrient-poor soils. CO2 emissions also decrease when fuel-powered various equipment are used less.

Implementing efficient tillage methods suitable to a farm is a known strategy in carbon farming. Carbon farming is an agricultural solution to climate change that provides payments to farmers who shift to climate-smart agricultural practices such as conservation tillage.

Examples of conservation tillage methods

• Reduced or minimum tillage: Tilling is minimised by combining operations to keep the number of tillage tasks as low as possible. For example, land preparation and seeding operations are combined in one pass with ploughing eliminated and crop residue retained.

• No-till: Also known as zero-till, eco fallow, or slot planting, no-tillage is the least intensive type of tillage where the soil is left undisturbed by eliminating tillage. Planting or drilling is done by injecting the seeds or nutrients in narrow slots in the seedbed. A specialised tool can be used such as row chisels or roto-tillers which have less fuel and labour requirements compared to other tilling methods.

• Ridge-till: Commonly used for crops like corn, soybeans, and cotton, tillage is reduced by preparing the seedbed only on shallow ridges formed during the previous season. Poorly drained soils or fields with little elevation are suited for this tillage method.

• Stubble or ridge-till: The goal is to cover the ground by leaving a good layer of crop residue on the soil surface which is then partially mixed with the soil using a disk or moldboard plough.

Getting paid with conservation tillage

Sequestering carbon in the soil can help mitigate climate change while improving soil health. Practices like minimising tillage to draw carbon into the soil is one method of carbon farming. Shifting to carbon farming practices in the form of conservation tillage with other climate-smart agriculture practices provide earnings to farmers along with other co-benefits.

Sources

• Khursheed S, Simmons C, Wani SA, et al. Conservation tillage: impacts on soil physical conditions–an overview. Adv Plants Agric Res.2019;9(2):342-346. DOI: 10.15406/apar.2019.09.00446. https://medcraveonline.com/APAR/conservation-tillage-impacts-on-soil-physical-conditionsndashan-overview.html

• Hussain, S. et al. Carbon Sequestration to Avoid Soil Degradation: A Review on the Role of Conservation Tillage. Plants 10, 2001 (2021). https://doi.org/10.3390/plants10102001. https://www.mdpi.com/2223-7747/10/10/2001

• Abdalla, M., Osborne, B., Lanigan, G., Forristal, D., Williams, M., Smith, P. and Jones, M.B. (2013), Conservation tillage systems: a review of its consequences for greenhouse gas emissions. Soil Use Manage, 29: 199-209. https://doi.org/10.1111/sum.12030. https://bsssjournals.onlinelibrary.wiley.com/doi/abs/10.1111/sum.12030

• Chen H., Dai, Z. Veach, A. Zheng, J. Xu, J. Schadt, C. (2020). Global meta-analyses show that conservation tillage practices promote soil fungal and bacterial biomass. Agriculture, Ecosystems & Environment. Volume 293, 2020, 106841, ISSN 0167-8809. https://doi.org/10.1016/j.agee.2020.106841. https://www.sciencedirect.com/science/article/pii/S0167880920300268