Efficient Water Use and Greenhouse Gas Emission Reduction in Agricultural Land Use—The Aspect of Land Consolidation

Abstract

Efficient water utilization and greenhouse gas emissions have become the topic of wide scientific interest in the last few decades. In this research, we considered the reduction in the road length and the increase in the irrigation channel length after land consolidation. The efficiency of water use is considered as the function of the distance between the water source and crops. The reduction of greenhouse gases is considered as the function of the reduction in the length of the agricultural mechanized transport. A simple mathematical model was developed for calculating the reduction of the road network transport length. The results showed that land consolidation (LC) reduces the road network length, by itself, and provides conditions for an increase in the irrigation channel length. In the case study area, the road network length was reduced by more than one-third (36.8%) and the irrigation channel length was more than doubled (125.9%).

1. Introduction

A comprehensive approach to minimize water use and reduce greenhouse gas emissions in agricultural activities is required by the fact that a significant amount of freshwater is used for irrigating crops, as well as the significant amount of greenhouse gas emissions caused by using agricultural machinery in crop cultivation.

The agricultural sector is a major user of both freshwater and groundwater. According to Calzadilla et al. [1], about 70% of all water is used for the agricultural sector, which is the main user of water including groundwater.

Different countries have taken different measures in order to address water scarcity. In Australia, the environmental effectiveness and economic efficiency of water use in agriculture were established through the idea of competition and markets as a paradigm of water management [2].

In China, 75% of the grain produced comes from irrigated lands [3]. Yet China faces problems of water use in agriculture, such as water shortages, pollution and transferring water out of agricultural use to low water-use efficiency. The research approach is based on grouping possible solutions into (1) solutions on the supply side, and (2) solutions on the demand side.

The Near East and North Africa are the regions with the lowest amount of fresh water per capita in the world. This is probably caused by a severe scarcity of water resources. The traditional assumption in these regions was that increasing irrigation efficiency would lead to substantial water savings. However, the evidence from the research showed that irrigation tends to increase rather than decrease total water consumption [4]. The significance of water also prompts the development of low-cost and reliable assessment methods for agricultural water requirements supported by remote sensing data and techniques [5].

Contrary to the positive effects of irrigation, even though the use of water is necessary for agricultural production, irrigation affects the soil characteristics because of salinization and other processes which are closely connected with irrigation. The problems to arable soil caused by irrigation have been well-known for a long time. Irrigation systems usually produce adverse effects on the soil, including erosion, salinization, alkalization, the loss of soil structure and waterlogging [6]. ”Some of the soil deterioration processes are very difficult to reverse and cannot be overcome by simple leaching and draining. Maximum efforts are needed to prevent these processes because the amelioration of waterlogged and secondary salinized or alkalized soils is expensive and complex [6]”. The solution to this problem is proposed through the careful management of soil and water to maintain the proper salt balance and which increases the efficiency of water use [7]. The importance of soil salinization is well understood by the FAO, and the organization made a map for a comprehensive overview of the state of soil all over the world [8]. Various models and approaches for solving the problem of soil salinization have been researched, and all of them are very complex, expensive, and do not support the possibility of solving soil salinity efficiently and completely [9,10].

Another source of problems in agricultural activities is the greenhouse gas emitted by utilizing machinery in agriculture. According to Binswanger [11], mechanization in agriculture is the most profitable and contributes the most to growth where land is abundant, the labor is scarce relative to the land, and the labor is moving rapidly off the land. This phenomenon (labor movement off the land) is especially present in contemporary civilization, which means that mechanization becomes a necessity for agricultural activities. In different countries, the contribution of agriculture to greenhouse gas emissions differs. For example: in the USA, it is 6.3% [12]; in Denmark, it is 12% [13]; while, in the UK, the contribution is between 20% and 30% [14]. The main cost-efficient ways for reducing emissions in agriculture are based on (1) increasing the use of improved machinery efficiency and farming practices, and (2) increasing the use of renewable energy sources [15].

An extreme case of agricultural production is rice cultivation, which not “only uses large amounts of irrigation water, but also produces significant methane (CH₄) emissions” [16]. According to Zhao et al. [17], “water&land resources exploitation on agricultural carbon emissions helps explain agricultural “water-land-energy-carbon-nexus” (WLEC) nexus and improve the efficiency of agricultural water and land use”.

Bearing in mind the estimation that 95% of food is directly or indirectly produced on soil, [18] and that soil, according to the data analysis and proof, is a non-renewable [19] and finite resource, it immediately follows that all reasonable efforts must be done to prevent its degradation and build the conditions for its recovery whenever possible.

Summarizing the effects of agricultural production, it is possible to conclude as follows:

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The soil is the base for food production, especially bearing in mind its non-renewability and limited area.

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The growing population, projected to increase from 7.3 billion in 2015 to 9.5 billion by 2050, necessitates an increase of 70% in agricultural production between 2005 and 2050 [20].

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The necessity of irrigation degrades soil by different processes, especially through salinization caused by the poor quality of the water.

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The scarcity of water leads to the development of different strategies for its use in agriculture, with the basic aim to increase its efficient use (to increase agricultural production with a decrease in water use).

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The mechanization in agriculture produces significant emissions of greenhouse gases.

These inevitable processes of soil degradation and the necessity of food production lead to the conclusion that the solution (in cases where the efficiency of water and the use of mechanization in agricultural production is high) can only be found from the aspect of the rearrangement of land in a way that minimizes the effects of land ownership fragmentation, land ownership dispersion and parcels’ improper shape and size. Grouping parcels and their rearrangement in a way that minimizes the negative effects on soil and atmosphere caused by irrigation and mechanization use is possible by land consolidation. Land consolidation allows not only for the grouping of parcels of one landowner but also the design of optimal irrigation systems and optimal road networks in the area of arable land. Land consolidation is defined in different ways but, in this paper, we have selected the definition which describes land consolidation as “agricultural infrastructure services such as irrigation, drainage, land levelling and soil conservation to make agricultural management economical and feasible” [21]. Of course, this definition does not exclude the basic idea that land consolidation solves the problem of land ownership fragmentation. In addition, the long and short terms of economical and feasible agricultural management should be emphasized here. In the short term, it is possible to obtain higher gains by intensive use of land and irrigation systems but, in the long term, with an absence of adequate actions for minimizing the negative effects of soil salinization, it might lead to land degradation and, consequently, could make the land unusable for agricultural production. This is an unwanted and impermissible scenario in light of the before-mentioned importance of arable land and its inevitable degradation during its use in agricultural production.

Land ownership fragmentation is a consequence of an existing land inheritance system, and it should be replaced by a system that prevents land ownership fragmentation and the miniaturization of farms [22]. Land ownership dispersion is defined as the distances between the plots of a single landowner, which is a significant source of inefficiency in agricultural production [23]. The size and shape of the parcels are also significant indicators of efficient arable land use [24]: the greater area of every single parcel and its better shape increase the efficiency of agricultural production. The size of a parcel is limited by other natural conditions, such as wind direction and speed, the geographical position of the arable land and other possible impacts, such as a risk of flood, etc.

In this research, the basic question is formulated in the direction of whether land consolidation (LC) can improve water efficiency use in the agricultural sector and reduce greenhouse gas (GHG) emissions. The research is focused on the transportation paths (reducing the road network length) and increasing the irrigation channel length during the process of LC. The research resulted in the conclusion that a simple model could explain the effects of LC on the reduction of GHG emissions in agricultural activities, and that the process of LC enables the increase of the irrigation channel length in the land-consolidated area. From the aspect of efficient water use and reduction of greenhouse gas emissions, it is possible to state that land consolidation is a necessary condition for sustainable agriculture and sustainable land use.

2. Materials and Methods

2.1. Material

The materials used for estimating the realized land consolidation are based on the consolidation of an area of land in the cadastral municipality Radenković—Sremska Mitrovica, Serbia. The considered area is located approximately at WGS coordinates φ = 44°54′20″ and λ = 19°30′00″. The researched area covers approximately 45 hectares, and it is considered a representative sample for a land consolidation project.

The research on the water influence on crop yields in the region of Vojvodina resulted in the conclusion that all crop yields, except soybean, were most responsive to changes in the GP and summer precipitation [25]. This conclusion is very important, because the seasonal variability shows that, in the considered area, in summer, about 200 mm of precipitation could be expected [26]. The study of aridity in Vojvodina [27] showed that, despite the high value of the De Martonne aridity index during the year in the considered area (29.8, which classifies those areas within the humid domain), during the summer it obtains values between 20 and 24, which brings the considered area into the Mediterranean domain of aridity. This fact justifies all reasonable efforts to increase the irrigation system in Vojvodina and in the considered area, as well. A reasonable attempt to improve irrigation systems could be undertaken through the project of land consolidation, which, by rearranging the ownership distribution, also makes possible the improvement of irrigation systems and road networks.

2.2. Method

Numerous methods for the consolidation of fragmented land ownership have been developed in order to improve the efficiency of agricultural land use. The optimal network of roads and channels should be designed from the aspect of efficient water use and the minimization of greenhouse gas emissions.

The approach based on trial and error in land consolidation is always burdened with a risk of potentially unsuccessful results. The special sensitivity of the land consolidation process is in the phase of public discussion about the designed parcel rearrangement. Many objective methods have been developed to decrease the risk of negative reactions from landowners and to reduce errors in the land consolidation process as much as possible. Those methods are based on the maximization or minimization of objective functions, depending on the objectives of the land consolidation designer.

The solution of the block prioritization by a transportation model, as a specific case of linear programming, could be obtained by the model [28] with objective function:

$$Z_{max}={\displaystyle \sum }{\displaystyle \sum }{F}_{ij}{X}_{ij}$$

(1)

where:

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$Z_{max}$—optimization function;

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$F_{ij}$—the block priority coefficient;

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$X_{ij}$—the amount of land in block $i$ which could be assigned to farm $j$.

This model was modified in order to encompass many more significant variables [29], such as the tillage time and rate of the area. The optimization process is then defined by the following equation:

$$Z_{min}={\displaystyle \sum }{\displaystyle \sum }{C}_{ij}{Y}_{ij}$$

(2)

where:

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$Z_{min}$—optimization function, meaning that it should be minimized;

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$C_{ij}$—the cost factor;

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$Y_{ij}$—the size of the area to be allocated for $i\mathrm{th}$ holding to $j\mathrm{th}$ block.

In this approach, the cost factor encompasses the road time index, the rate of the area and preference factor of $i\mathrm{th}$ holding to $j\mathrm{th}$ block.

According to Bugaienko [30], the main goal of the modelling is to minimize the distance from the parcel to the farmhouse. This makes sense because the mechanized transport line from the farmhouse to the parcel could be considered a fixed cost in agricultural production and, also, an unnecessary source of greenhouse gas emissions in agriculture. Bearing in mind that agricultural mechanized transport from the farmhouse to the parcel and back is an inevitable activity in agricultural production, only its minimization actually minimizes the greenhouse gas emissions caused by agricultural mechanization.

In the paper by Aslan et al. [31], the landowners’ requests were included into the process of land consolidation. The model used for evaluation in accordance with the landowners’ requests and the optimal reallocation of the parcels was one developed by Stützer [32]:

$$\mathrm{DF}={\displaystyle \sum }\mathrm{A}\ast \frac{{\displaystyle \sum }\left(\frac{\mathrm{Pwg}}{\mathrm{Gg}}\right)}{{\displaystyle \sum }\mathrm{Pwg}}-{\displaystyle \sum }\mathrm{F}\ast \frac{{\displaystyle \sum }\left(\frac{\mathrm{Pwn}}{\mathrm{Gn}}\right)}{{\displaystyle \sum }\mathrm{Pwn}}$$

(3)

where:

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$\mathrm{DF}$—distribution function;

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${\displaystyle \sum }\mathrm{A}$—the sum of the decreases in the amount of over-allocation in the block when the landowner’s first request is not enacted vs. when the first request is enacted;

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${\displaystyle \sum }\mathrm{F}$—the sum of the increases in the amount of over-allocation in the block when the landowner’s other request is enacted vs. when the other request is not enacted;

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$\mathrm{Gg}$—$\mathrm{PF}$ (priority factor) of the current request;

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$\mathrm{Gn}$—$\mathrm{PF}$ of the other request;

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$\mathrm{Pwg}$—amount of the current request;

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$\mathrm{Pwn}$—amount of the other request.

If the $\mathrm{DF}$ value is greater than zero, it means that an agreement between the landowners’ requests and the optimal solution exists. In the opposite case, when the $\mathrm{DF}$ value is lower than zero, it means that an agreement between the landowners’ requests and the optimal solution does not exist.

The complexity of an optimal solution in the process of land consolidation is researched also by extending the parameters and indicators of land consolidation, including the shape and size of parcels and the transport costs as a mixed integer programming problem [33]. Land consolidation, from a historical perspective, primarily solved the problems of production and habitation, but the modern approach requires the consideration of environmental and cultural demands [34].

Determining the distances in the land consolidation process also could be an issue from different aspects. The distances could be determined by the coordinates of different points: the barycenter of the farms, the actual locations of farmsteads, the centroids of the plots and the local transport network [35]. This particular study encompassed four sets of distances: three rectilinear between the centroid of the plot and the farmstead, the village center and the barycenter of the farm’s land, and one between the farmstead and the plots, considering the shape of the road network. This study showed that it is possible to reduce the transport path length between the farm center and parcels significantly and to reduce the fuel consumption, accordingly, with the path length (i.e., the greenhouse gas emissions) [36].

The common challenge for all the optimization methods is to reduce the transport path from the farm center to the parcel center. The optimization of the transport length can be expressed with the equation:

$$Z_{min}={\displaystyle \sum }{D}_{ij}$$

(4)

where $D_{ij}$ is the distance from $i\mathrm{th}$ farm to $j\mathrm{th}$ belonging parcel. Distance $D_{ij}$ should be measured from the farm (from the point where the mechanization sits) to the entry point of the parcel. The term $Z_{min}$ refers to the minimum possible sum of the distances between the farms and belonging parcels in the land consolidation solution. This objective function could be determined in the process of the land consolidation design, i.e., this is the desired objective function, while the realized distances could be measured only after the land consolidation is finished. The minimization of distances might be limited by other requests and difficult to realize. The realized function can be expressed as follows:

$$Z_{realized}={\displaystyle \sum }{D^{\prime }}_{ij}$$

(5)

where ${D^{\prime }}_{ij}$ is the distance from the farm to the parcel, obtained after the land consolidation.

The difference between the designed and realized objectives reads:

$$\Delta Z=Z_{min}-Z_{realized}$$

(6)

If $\Delta Z=0,$ it means that the realized and designed objective functions are equal; if $\Delta Z>0$, it means that the realized land consolidation is worse than the designed; and, if $\Delta Z<0,$ it means that the realized land consolidation is better than the designed.

Another possibility for evaluating the land consolidation is to compare the situation before the land consolidation with the optimized model and realized values, as follows:

$$Z_{BLC}={\displaystyle \sum }{D}_{ij}^{BLC}$$

(7)

$$\Delta Z_{min}^{BLC}=Z_{BLC}-Z_{min}$$

(8)

$$\Delta Z_{realized}^{BLC}=Z_{BLC}-Z_{realized}$$

(9)

where:

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$Z_{BLC}$—the sum of the distances between the farms and belonging parcels before the land consolidation;

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$D_{ij}^{BLC}$—the distance from the $i{\mathrm{th}}^{}$ farm to the $j{\mathrm{th}}^{}$ belonging parcel before the land consolidation;

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$\Delta Z_{min}^{BLC}$—the difference between the sum of the distances before the land consolidation and the designed arrangement of the parcels;

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$\Delta Z_{realized}^{BLC}$—the difference between the sum of the distances before the land consolidation and the realized arrangement of the parcels.

It is expected that $\Delta Z_{min}^{BLC}$ and $\Delta Z_{realized}^{BLC}$ should be greater than zero, i.e., the sum of the distances before the land consolidation should be greater than the designed and after the land consolidation. In the case of flat terrain, the fuel consumption should be proportionately lower than the reduced path length.

As a further development of Equation (4),

$$Z={\displaystyle \sum }{D}_{ij}$$

could be directed in a way to separate the total distance from the ith farm to the jth belonging parcel in two terms: the distance between the ith farm to the entry point of the group of land-consolidated areas, and from the entry point to the jth belonging parcel. This could be explained by the following equation:

$$Z={\displaystyle \sum }\left(D_{iEP}+D_{jEP}\right)$$

(10)

where:

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$D_{iEP}$—the distance from the farm to the entry point of the land-consolidated area; and

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$D_{jEP}$—the distance between the entry point and the jth parcel.

Taking into consideration that the $D_{iEP}$ cannot be changed, because the position of the farm will remain after the land consolidation in the same place where it was before, only the distance $D_{jEP}$ can be the variable of the process, and reducing these distances can reduce the transportation distance by agricultural machinery. The rearrangement of the last equation leads to:

$$Z={\displaystyle \sum }{D}_{iEP}+{\displaystyle \sum }{D}_{jEP}$$

(11)

It is obvious that minimizing the second term could contribute significantly to reducing the transportation distance, which is the main objective of the road network optimization. Taking into account that the landowners’ requests might limit the optimization of the road network, it can be concluded that the road network is almost always sub-optimized. Finally, the optimization of the road network comes down to the following equation:

$$Z^{\prime }={\displaystyle \sum }{D}_{jEP}$$

(12)

where $Z^{\prime }$ refers to the sum of the road length from the entry point to each parcel in the land consolidated area.

The final effect of the land consolidation on the road network can be explained by the following equation:

$$\Delta Z^{\prime }={Z^{\prime }}_{ALC}-{Z^{\prime }}_{BLC}$$

(13)

where ${Z^{\prime }}_{ALC}$ refers to the sum of the road lengths from the entry points to the parcels after the land consolidation.

The irrigation network is determined by the available water resources and terrain topography. Considering the actual conditions, it is necessary to provide the available water resources as near as possible to every parcel in the land consolidation area and to minimize crossing road networks. The way to reduce greenhouse gas emissions in the process of building irrigation systems is to build the channels in an ecological manner, with lower demand for material transport, and to build biological filtration ponds, which can be used as drainage systems [37]. Filtration ponds can also be a tool to facilitate the desalinization of arable land.

The water resource availability is expressed by the length of the irrigation channels before and after the land consolidation:

$$\Delta C=C_{ALC}-C_{BLC}$$

(14)

where:

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$\Delta C$—the difference in channel length after and before the land consolidation;

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$C_{ALC}$—the channel lengths after the land consolidation;

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$C_{BLC}$—the channel lengths before the land consolidation.

It is expected that the following condition should be fulfilled:

$$\Delta C\ge 0$$

(15)

From the aspect of the sustainable use of land defined by minimizing greenhouse gas emissions, the efficiency of agricultural production and land preservation, it immediately follows that land consolidation shall provide:

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A minimal transportation length of agricultural mechanization; and

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Irrigation/drainage systems that provide water when it is lacking and minimizes water retention in the case of a flood.

The final solution of land consolidation is the combination of the optimal solution and the landowners’ requests; landowners’ requests could lead to a suboptimal solution.

Bearing in mind the numerous parameters in the land consolidation process and the potential obstacles, it is better to understand all the modeling tools as a decision support framework [38] rather than as the ultimate tools.

3. Results

The main characteristics of the considered area before the land consolidation were as follows:

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The absence of access roads to the many parcels;

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The irregular shapes of the parcels;

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The dispersion of the ownership;

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The existence of small parcels;

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The absence of irrigation systems.

The form of the considered land for the consolidated area is shown in Figure 1 (source: google earth).

The area of the parcels before and after the land consolidation with the road and channel networks are shown in Figure 2 and Figure 3. In Figure 2, the position and shape of the parcels before the land consolidation, as recorded in the cadastral authority, are shown. In Figure 3, the position and shape of the parcels with the road and channel networks, after the land consolidation, are shown.

The results obtained in the considered area after and before the land consolidation are given in

Table 1. The length of road and channel networks after and before land consolidation.

	Length of Roads Network [m]	Length of Channels [m]
After LC *	1810	2196
Before LC *	2866	972
Difference	−1056	1224
Relative difference per hectare	−23.5	27.2
Relative difference in %	−36.8	+125.9

* LC—Land Consolidation.

.

As shown in Table 1, in the considered area, the following results were finally obtained:

$$\Delta Z^{\prime }={Z^{\prime }}_{ALC}-{Z^{\prime }}_{BLC}=1810 \mathrm{m}-2866 \mathrm{m}=-1056 \mathrm{m}$$

$$\Delta C=C_{ALC}-C_{BLC}=2196 \mathrm{m}-972 \mathrm{m}=1224 \mathrm{m}$$

The obtained results show that the transport length for agricultural mechanization is reduced by 1056 m after the land consolidation in the area of approximately 45 hectares. This means that the relative reduction in the transport length is approximately 23.5 m per hectare. The results also show that the relative increase in the channel length per hectare is approximately 27.2 m. The relative difference for the mechanized transportation is −36.8% in length and +125.9% for the channels’ length.

This case study shows that land consolidation has significant potential to shorten the length of agricultural mechanization and increase the length of irrigation channels. This potential of land consolidation indicates the possibility of reducing greenhouse gas emissions and preserving agricultural land quality in the process of agricultural production.

The distribution function, in this case, did not increase the over-allocation of parcels because it was only one of the requests resolved in the process of the land consolidation design. This illustrates the importance of communication with landowners during the process of land consolidation design. This could also be the result of the relative simplicity of the considered area but, in more complicated cases, this could the critical factor for successful land consolidation.

4. Discussion

Land consolidation in the literature and practice is considered an appropriate activity, which results in many useful effects connected with agriculture and land utilization. It is also an important policy instrument that contributes to sustainability [39]. Keeping in mind that sustainability is the subject of the 17 Sustainability Development goals defined by the UN [40], which are devoted to social and environmental factors, it suggests that the base for food production, which agricultural land certainly is, should be treated in a sustainable way as much as possible. This means that, from the aspect of this paper, land consolidation should minimize the negative effects of agricultural land utilization and maximize the duration of its quality.

The significance of water utilization can be illustrated by the practices in developed countries. In countries belonging to the Organization for Economic Co-operation and Development (OECD), great attention is given to water use in agriculture, especially for irrigated areas. The available data for changes in both water use and irrigated areas [41,42] were analyzed. The obtained results showed that, according to a simple average method, the average water use increased by 0.15 million liters per hectare [ML/ha] (from 5.23 ML/ha to 5.38 ML/ha) in the considered period (1990–1992 to 2002–2004), but the weighted mean (using the irrigated area as a weight for each country) showed that water use decreased by 0.49 ML/ha. Figure 4 shows the changes in agricultural water use in ML/ha and the irrigated area in Mha.

External factors, as well as agricultural technologies, also influence soil structure. The significance of technology in the quantitative and qualitative evaluation of agricultural production is demonstrated by the research on how fertilizers impact soil microbial and enzymatic activity [43], how the utilization of nanotechnology impacts agricultural practices, [44] and, of special interest, the long-term effects caused by organic and mineral fertilizers [45]. All this research is fundamental for future agricultural development, but it cannot solve some inevitable effects of agricultural activity which produce GHG emissions. In addition, efficient water use in agricultural activities seems to be a permanent subject of research.

According to the obtained results, it can be concluded that land consolidation possesses significant potential for reducing the length of agricultural mechanized transport from the farmhouse to a particular parcel, as well as increasing the length of the irrigation system. In this case study, the results show that the reduction in the mechanized transport length was, in total, 1056 m or 36.8%, while the length of the irrigation channel was, in total, increased by 1224 m or +125.9%.

Both the reduction in the transport length and the increase in the irrigation system length should increase the capacity of agricultural land utilization from the aspect of sustainable agricultural land utilization. The reduction of the agricultural mechanized transport length also reduces the greenhouse gas emissions, while the increase in the channel length increases the possibility of irrigation, as well as the drainage of land in the case of a flood, and, also, reduces the groundwater level. It is necessary to stress the fact that, without the project of land consolidation, these results would be practically impossible to obtain.

The positive effects of land consolidation can be expressed in a simple way: it allows the rearrangement of parcels (land ownership) in a manner that enables the best possible sustainable agricultural land use. Sustainable agricultural land use means that agricultural land should be used in a manner to preserve it at a certain level of quality or, if this is not possible, then its degradation should be at a level that does not put its use at risk in the future. As derived from the considered level in this research, the degradation of agricultural land means an increase in salinization (caused by irrigation) and an unnecessary use of agricultural mechanization (its utilization over the necessary level). In this sense, the role of land consolidation is to rearrange parcels in a way that maximizes the efficiency of water use, increases the efficiency of soil desalinization and minimizes the utilization of agricultural mechanization.

Regarding the basic goals connected with land use (food production and preservation of agricultural land) from the aspect of the imperative of agricultural production in the future, it is obvious that these goals are in conflict. The pressure for food production (requirements for irrigation and the use of agricultural mechanization) leads to arable land degradation, and the consciousness about the significance of arable land should limit its use in the future, i.e., compel humanity to find ways for its sustainable use. Taking into account that arable land is a limited and non-renewable resource necessary for food production requires careful use now in order to keep it productive in the future. The only possible way to postpone arable land degradation is to rearrange it in a manner that decreases the negative effects of soil salinization and reduces the emission of greenhouse gases. Soil salinization can be decreased by improving the efficiency of water use in agricultural production (by increasing the size of parcels and optimizing the irrigation systems) and by utilizing the suitability for soil leaching. The reduction of greenhouse gas emissions is only possible by reducing agricultural mechanized transport lines, which is done by optimizing the road network. Both the reduction of soil degradation and greenhouse gas emissions is possible during the process of land consolidation, but only if those goals are set in advance, i.e., in the phase of defining the land consolidation goals.

The conflict of goals immediately directs us to the conclusion that only optimization processes can lead to an acceptable solution. It means that not all goals may be fulfilled completely (the arable land cannot be preserved at the present level in the future, and the pressure on food production should not be in a manner that deteriorates the arable land or significantly reduces its quality, including its potential for food production and its mechanical, physical, chemical and biological characteristics). This problem can be addressed at a lower level and simplified in two ways: to minimize the requirements for water and to minimize the utilization of agricultural mechanization by reducing transport lengths. Even on this level of simplification of the problem, the conflict between these goals could still exist in cases where the optimal road network could cause a suboptimal irrigation infrastructure and vice versa. Geographical limitations and other factors could also influence the optimal solution. In this research, methods for road network and irrigation system optimization are discussed, and a simple method for optimization is proposed and utilized as an example in practice.

This study considered only the changes in the agricultural mechanized transportation length and changes in irrigation channel length as direct consequences of land consolidation. Those changes can be considered as only possible for realization in an efficient way if they are realized during the process of land consolidation. The primary benefits of the agricultural transportation length reduction are (1) the reduction of the necessary costs of agricultural mechanized transportation from the farmhouse to the parcel, and (2) the reduction of greenhouse gas emissions caused by the agricultural mechanized transportation. The increase in irrigation channel length provides the water that is a necessary condition for crops growing. The irrigation channel is also used for draining the parcels in case of a flood. This study does not encompass the total effects of land consolidation on the road network, especially the effects on tillage time and the agricultural mechanized transportation length from the farmhouse to the entry point (the common point for entry in the land-consolidated area). The tillage time is dependent on the parcels’ shape and the characteristics of the agricultural mechanization.

5. Conclusions

In this research, the effects of land consolidation on sustainable agricultural land use were considered through the analysis of road and irrigation channel networks. The model utilized is based on the reduction in agricultural mechanized transport lengths and the increase in irrigation channel lengths in the land consolidation case study provided in a part of a cadastral municipality of Radenković—Sremska Mitrovica, Serbia. This research shows that land consolidation possesses a significant potential for the reduction in the length of agricultural mechanized transport from the farmhouses to the parcels, as well as the potential for irrigation improvement. Land consolidation, by itself, provides the rearrangement of land ownership and enables the shortening of road networks and extension of irrigation channels in the most efficient manner, even in cases when that is not its main goal. Bearing in mind that these results would be practically impossible without land consolidation, it immediately follows the imperative of land consolidation to establish the sustainable use of agricultural land. The results of land consolidation in the considered area show its significant potential to reduce GHG emissions and to provide possibilities for efficient water utilization, including the increase in irrigation. Further investigations should include the specific costs of tillage time, analysis and further investigation of the possibilities of irrigation development systems.