**2. The relevance of soil compaction and its effects on sustainability**

Interest in soil compaction dates back to the time when humans started to use draft animals as a main source of power in agriculture. Many authors have addressed the problem since the 19th century. One of the first recognitions of the problem in academic literature dates back to 1857, with a description of the Fowler steam enginepowered plowing system [1]. Draft animals are still being used on vast areas of land in developing countries, and the animal-induced compaction problem continues to this day. The growing use of steam-powered tractors added to soil compaction concerns in the second half of the 19th century. While the mass-power ratio allowed for the widespread use of powerful tractors, the vehicles were still very heavy, and the need to minimize wheel impact on the soil was quickly recognized.

Different engineers have attempted to address the problem in multiple ways. These attempts did not lead to a unified design, but they moved the engineering thinking forward and were instrumental in creating the more successful designs of the 20th century. Between the last decade of the 19th century and 1904, internal combustion engines (ICE) replaced steam engines on tractors in America, and a new era of agriculture began. The better mass-power ratio of the ICE provided for lighter designs and less impact on the soil, but other problems emerged. Mass agriculture meant the

### *Reducing Soil Compaction from Equipment to Enhance Agricultural Sustainability DOI: http://dx.doi.org/10.5772/intechopen.104489*

more intensive use of fields and more impact on the soil per given period in time. One of the first experiments describing soil compaction problems was run in 1944. The topic has continued to be a strong focus for agricultural researchers. Raney, Edminster, and Allaway conducted the first review of literature on compaction in agricultural soils in America, which included 43 references [2]. The so-called "load index" started to grow at about the same time and exceeded that of the early 20th century by the 1970s. The soil compaction problem continues to be of a major focus of agricultural, industrial, and academic practitioners and researchers. One industrial example is Caterpillar's efforts to use tracks in agriculture in agriculture to decrease soil compaction [3]. Other modern solutions have attempted to address the problem, and the current review will introduce them to the reader [4–6].

#### **2.1 Environmental impact of soil compaction**

Soil compaction has a measurable influence on the environment, specifically on atmospheric, water, and soil resources. Agricultural operations have a major impact on the atmosphere through the emission of greenhouse gases. Soil "compaction may change the fluxes of these gases from the soil to the atmosphere because of its influence on soil permeability, soil aeration and crop development" [4, p. 8]. Water resources include both surface and ground water volumes. Soil compaction negatively affects the infiltration of different substances into the ground. Ammonia injected into the soil can escape into the atmosphere faster in a compacted soil than in an uncompacted one. Soil compaction also perpetuates the accumulation of rainwater on the surface in low parts of the field and increases the likelihood of runoff events. The latter leads to excessive sediment and chemical transfer into surface ground water resources, such as local rivers, lakes, ponds, and bigger regional natural water reservoirs [5, 7].

Soil biota is responsible for the decomposition of organic matter, release of nutrients and formation of aggregates [8]. Such tasks are performed by microfauna (bacteria, fungi), which are fed upon by meso- and macrofauna (protozoa, nematodes, arthropods) within the soil food web. **Figure 1** illustrates some of these various interconnections between the living things in the soil.

Soil compaction creates a rearrangement of soil particles that leads to a reduction of void space, a phenomenon that can be measured in several different ways. At first glance, there are visual and tactile methods that can provide a quick assessment, but to quantify the effects of soil compaction, physical parameters must be measured. Direct and indirect measures are used together to enable a deeper understanding of the characteristics of the total volume of the soil, such as bulk density (direct), soil strength (indirect), soil electrical resistivity (indirect) and water infiltration rate (indirect). **Figure 2** shows two examples of soil profiles exhibiting compaction effects. The soil on the left has a better structure above and below the compacted layer located between 10 *cm* and 40 *cm* depth [9]. On the right, a compacted layer in wetland creates a toxic environment for roots and soil biota. Soil compaction effects vary by location based on multiple interconnected factors, making a comprehensive assessment of specific fields the key to securing the sustainability of any agricultural operation over time.

### **2.2 Effects on harvest quality and farmlands**

Soil compaction has a directly visible effect on the crop that is being grown in the degraded area. As soil compacts, it reaches a point of root growth restriction that is

**Figure 1.** *Soil biota species and food web (duiker, 2005) – [8].*

#### **Figure 2.**

*A compacted layer under dryland canola (left), and a gray anaerobic layer in a clay loam soil (right) (Nawaz et al., 2013) – [9].*

highly detrimental to both the quality and health of plants, as well as the quantity of the cultivated crop yield [10]. The lack of loose soil aggregates prevents strong root formations. This leaves crops more susceptible to wind and water damage. There is reduced nutrient uptake, since the root mass of the plant is diminished in both absorption volume, as well as effectiveness. Individual plants are less healthy and produce significantly less grain and forage mass. Perennial crops, like many fruit plants, stop root growth when confronted with significant compaction. Beyond the lack of void space, nutrient uptake in compacted topsoil is greatly reduced as the biological health of the soil diminishes [11]. Crops growing in densified soils can be expected to be brittle, due to the reduced nutrient intake as soil compaction causes reduced aerobic microbial activity and denitrification [12]. Soil compaction has a progressively negative effect on the biosphere. As the soil is compacted and continuously depleted, natural vegetation, such as weeds and grasses, quickly gets restricted from lack of soil aeration. The crushing of the soil and diminishing amount of

*Reducing Soil Compaction from Equipment to Enhance Agricultural Sustainability DOI: http://dx.doi.org/10.5772/intechopen.104489*

additional biomass that would otherwise be introduced into the soil can eventually lead to an elimination of plant life causing an open and exposed soil surface. Soil in this condition is more easily impacted by wind and water erosion. If preventative measures are not taken, the effects of soil compaction on crop quality and farmland are cumulative, can take place quickly, and have lasting damage [13].

As shown by a review of the soil compaction literature [14], studies detailing the continuing long-term effect of compaction on a specific piece of ground are rare. However, as shown in **Figure 3**, it can take years for soil to naturally recover following a single compaction event [15]. Studies in cotton, as displayed in **Figure 4**, show a significant decline in crop yield within the initial season of the compaction event [16]. Since the effects of compaction are cumulative and continue from one season on into the next, it can be inferred that the decline from unmitigated soil compaction will continue to grow and magnify under the same management processes. **Figure 5** presents the general effect over time on production costs and gross margin of the farming operation [14].

#### **2.3 Social and economic impact**

Soil compaction has a negative impact on the economy of agricultural operations in the long-term. Soil compaction decreases the quantity and quality of harvest. Continuous and unaddressed soil compaction does not allow soil to sustainably recover through natural means [17, 18]. This affects the local food security in the regions where the traditional economy relies on agriculture. The local quality of life and general economic health of an agricultural region is adversely affected when local soils become compacted. Multiple potential solutions can help minimize the impact. Some come from farmer experience and depend on the operator in the field. Others are industry-wide, general practices. Academic researchers model the problem by studying economic impact. These models provide for better forecasting, equipment selection, and targeted problem solving. One model suggests that in the short-term, the negative impacts of soil compaction can be compensated by "more timely field

**Figure 3.** *Yield recovery following a significant compaction event (Voorhees, 1986) – [15].*

**Figure 4.**

*Difference in same year cotton yield between compacted and uncompacted ground (Jamail et al., 2021) – [16].*

#### **Figure 5.**

*The generalized trends for production cost and gross margin for avoided compaction, relieved compaction, and compacted soils in production (Chamen, 2015) – [17].*

operations." Profits and productivity generate energy costs, air pollution, capital costs, timeliness costs, and soil erosion, which are also evaluated [19]. Other studies address the problem through even more sophisticated modeling. Additional effort is

## *Reducing Soil Compaction from Equipment to Enhance Agricultural Sustainability DOI: http://dx.doi.org/10.5772/intechopen.104489*

needed to standardize the corporate and academic researchers' efforts to improve these models for specific predictive tasks. Soil compaction models have the potential to help the businesses and governments to develop advanced solutions for real-world agricultural problems through an improved understanding of the social and economic impacts.

The extent of the economic effect of soil compaction is difficult to quantify as it is ultimately very situational. Under circumstances where soil requires additional operation to alleviate the effects of long-term compaction, the cost of crop production rapidly increases to unviability. Soil health does not always deteriorate to the point where intervention is required, but this does not mean that these farming operations are unaffected. The most common issue caused by soil compaction is the decrease in crop productivity. **Figure 6** below summarizes the impact soil compaction has on soil and crop health [20]. Reduction in plant growth and development, such as biomass accumulation, stomatal photosynthesis, and poor proliferation, as well as poor nutrient and water uptake decrease yield and overall crop productivity. **Figure 7** depicts the impact on potato yield resulting from varying irrigation levels [21]. This graph shows the availability of adequate water can increase yield by at least 100%. Because soil compaction so negatively impacts water availability and uptake, the conclusion can be drawn that compaction issues can decrease crop yield and productivity by up to 50%. In short, this also means that farmers risk losing 50% of expected profits, when the soil compaction problems are not properly addressed. Inattention to this vital issue in land management can destroy the resource's ability to be productive both now and in the future. It is imperative that farm managers understand the connection between management of soil compaction today and the long-term sustainability of the agricultural ground into the future.

#### **Figure 6.**

*Summary of the knowledge of the effects of soil compaction on soil plant morphological and physiological growth and soil properties (Shah et al., 2017) – [20].*

**Figure 7.** *Potato yield at different irrigation levels for subsoil and control fields (Ghosh & Daigh, 2020) – [21].*
