REVIEW

Soils dedicated to cattle rearing in Cuba: characteristics, management, opportunities and challenges¹

Los suelos dedicados a la ganadería en Cuba: características, manejo, oportunidades y retos

Sandra Lok Mejías

ABSTRACT

This study reviews the state of soils dedicated to cattle rearing in Cuba, opportunities for a proper use and main challenges to guarantee their improvement and conservation. It is highlighted the progressive deterioration and the factor or factors that limit in 90.6 % the usable agricultural area of the main cattle enterprises from the country. An amount of 45 % has low natural fertility and 30.3% have low effective depth. This study shows the advances of agro-ecological management of soils and its maintenance and improvement may be possible if cultural practices that benefit their processes and functions are implemented. In addition, it is reported the main studies conducted in this subject during the last years, and challenges for research are stated, as well as the development of knowledge on soil in cattle rearing areas.

Key words: soils, cattle rearing, opportunities, challenges.

RESUMEN

Se reseña el estado de los suelos dedicados a la ganadería en Cuba, las oportunidades para su uso adecuado y los principales retos para garantizar su mejora y conservación. Se destaca el deterioro progresivo y el factor o los factores que limitan en  90.6 % el área agrícola utilizable de las principales empresas ganaderas del país,  45 % poseen baja fertilidad natural y 30.3% son de poca profundidad efectiva. Se muestra que existen avances en el manejo agroecológico de los suelos, y que su mantenimiento y mejora puede ser posible si se emplean prácticas culturales que beneficien sus procesos y funciones. Se informa además, de los principales estudios realizados en la temática en los últimos años y se plantean los desafíos para la investigación y el desarrollo del conocimiento del suelo en las áreas ganaderas.

Palabras clave: suelos, ganadería, oportunidades, retos.

INTRODUCTION

Soil is the natural resource that, through history, has provided livelihood to human population. However, growing world population and their demand of food provoke, every day more, the increase of pressure on this means. In tropical areas, there are people searching for alternatives to preserve soils because it has been confirmed that it is not the warm weather which prevents a proper production of soil, but the inadequate management of them (Sánchez et al. 2011).

Soil deterioration is the threshold of desertification and constitutes a contemporary ecological problem of major importance in developing countries (Botero 2001). This process is defined as “the decrease or destruction of biological potential of this natural resource due to its bad use and management, and produces degenerative processes from the physical, economic and social environment in their surroundings” (The International Bank for Reconstruction and Development and The World Bank 2007). Their main processes are degradation of plant cover, water and air erosion, salinization, acidification, and physical, chemical and biological deterioration (García et al. 2012). All of them, likewise, have an inevitable contribution to the loss of their fertility and, therefore, their agricultural productivity.

 Latin American soils have 45 % of losses of their natural fertility, while in Cuba, 43 % is affected by erosion and 70 % shows low content of OM, among other factors that confirm the loss of fertility and the need of management for allowing recovery, improvement and preservation. Cattle rearing is characterized by using those soils of lees productive value and, therefore, the previously cited characteristics increase in them.

The objective of this study is to review the state of soils dedicated to cattle rearing in Cuba, opportunities for a proper use and main challenges to guarantee their improvement and conservation.

GENERAL CHARACTERISTICS OF SOILS DEDICATED TO CATTLE REARING IN CUBA

Soil sciences in Cuba started with studies of Hugh H. Bennett and Robert Allison, who researched on soils related to sugar cane. These authors introduced the classification of soils based on the America System of Series and Families. Later, the first scientific publications related to this subject were written: The Soils of Cuba (Bennett and Allison 1962) and Some New Cuban Soils (Bennet 1932).

Specific studies in areas dedicated to cattle rearing started after the revolutionary triumph, with the development of institutions devoted to achieve a development in agriculture and animal husbandry.  

• Brown (sialitic brown), representing 27.3 % of the area with 2.4 MM ha

• Ferrallitic, with 23.6 % and 2.0 MM ha

• Vertisol, representing 12 % of the area, with
1.0 MM ha

Agro-productive categories of soils are classified into: I) soils that allow crops to show their 70 % of their potential, II) soils that favor between 51 and 70 %, III) those that admit between 30 and 50 % and IV) those that only achieve 30 % of their potential.

Results of studies on crops with national economic importance show that 23.2 % of the studied area is classified from productive to very productive (category I and II), which indicates that yields superior to 50 % of the potential may be obtained in a wide range of crops. However, 76.8 % of the national agricultural area have soils classified from low to very low productivity (category III and IV), affected by edaphic factors that prevent them to reach potential yields. Therefore, it is necessary to widen the measures for their conditioning and improvement, so their productivity increases. Areas dedicated to cattle rearing are presicely located in soils with these characteristics.  

The Instituto de Suelos, during the year, conducted agrochemical studies in the main cattle enterprises in Cuba (table 1). These enterprises have 310,269 ha as total agricultural area, which are equivalent to 12 % of the area dedicated to animal husbandry. Out of them, 77,562 ha (25 % of the area under evaluation) were sampled. The highest production of milk and meat belongs to these enterprises, which also have the highest concentration of cattle (Instituto de Suelos  2015b).

The analysis indicated that 90.6 % of the agricultural usable areas of the evaluated cattle enterprises in all the country was affected by one or more limiting factors: 45 % with low natural fertility, which is the most frequent characteristic of cattle rearing soil; 30.3% with low effective depth, which reduces the volume of water and nutrients, available for radicular system; 20.5 % with low capacity of humidity retention, which is mainly present in sandy soils; 22 % shows an irregular topography, which derives into low effective depth, erosion and fast losses of humidity; 7.4 % contains salinity, which is associated to toxicity, increase of osmotic pressure and unfavorable physical conditions; 29.7 % have bad drainage, which affects the balance of water and air in the soil and favor compaction; 26 % shows acidity, which affects the availability of some essential nutrients or the increase of toxic elements like aluminum; 11.8 % are rocky soils, which decreases the volume of available soil to exploit due to the roots that provoke mechanical damages to plants and animals, take part of the decrease of water and nutrients storage and of the sowing labors of grasses and forages. 

This performance is a product of inadequate management through the use of agricultural practices and the application of technologies that were not in accordance with properties and edaphic potentialities. In addition, it is a consequence of overexploitation of agro-ecosystems, of the excessive use of fertilizers or the lack of its application. Other problems are the systematic occurrence of extreme climatic phenomena, lack of efficient monitoring mechanisms and control of soil fertility, and inefficient management policies insufficient efforts for improving training of producers.

Hernández et al. (2005) stated that one of the most difficult and complex problems to solve is the rational and optimal use of soils in humid tropical areas, without reaching, up to now, defining or conclusive results that allow to diagnose the most proper use and management according to the bio-physical environments that characterize each ecosystem.

Productive diversification and efficient use of available resources should be essential for guaranteeing soil life and improving life quality of the population (Vargas 2015). In this sense, competitivity of agroecological strategies to manage soil will be determinant.

AGROECOLOGICAL MANAGEMENT OF SOILS IN CATTLE REARING

Grassland ecosystems show open vegetation dominated by herbaceous species, which primary production is directly used by herbivorous (Miller 1990). They may be also formed by the harmonic union of herbaceous, shrub, tree and other species that originate the silvopastoral systems. They are usually located in areas with soils of relatively low productivity, inadequate for intensive agricultural uses (Kaine and Tozer 2005). In them, grazing is an efficient procedure to collect and transform their primary production in products for human consumption and use. In addition, their dungs and urine may contribute to nutrient recycling.

Composition and productivity of grasses is regulated by the activity of herviborous and the fact that its management requires to count with other trophic level implies an added degree of complexity to the ecology applied to management of natural resources (Quero et al. 2007).

Huss et al. (1996) and Yado (1996) define “grassland” as any area that produces pasture for cattle intake. According to these authors, there are two main types of grasslands: natural and artificial. The main difference among them lies on management intensity and cultural treatments they receive. Natural grasslands are those lands seating native grass for animal intake. Artificial grasslands are grassing lands with intensive management, which usually have introduced forage species and receive cultural practices.

 According to Sánchez et al. (2005), grasslands, regardless of type, are composed of biotic and abiotic elements that complete an indissoluble unity, and the proper functioning of the ecosystem depend on their dynamics and harmony. The abiotic components include inorganic substances involved in material cycles, climate regime, soil, topography and altitude. Biotic elements include autotrophic organisms or plants, organic matter consumers and disintegrators, like bacteria, fungi, nematodes and others. All components have specific functions and interact with each other, so that productive stability of grasslands and their persistence in time depend on the dynamic equilibrium between the parts of the system.     

Soil is a key component of these agro-ecosystems. According to Milera (2013), it is the base of the pyramid to achieve their appropriate ecological management. Soil conservation contributes to maintain their health and quality. Reaching its proper functioning, which is manifested through the state of their physical, chemical and biological properties, allows to obtain a sustainable agricultural productivity with positive environmental impact.

Likewise, edaphic conservation is related to soil resilience, which is its ability to recover its functional integrity after a disturbance, maintaining dynamic balance in their processes and functions (Obando et al. 2011). When the soil is continually disturbed, its ability to restore the dynamic balance of its functions decreases and requires the application of good management practices in order to recover. When disturbances are repeated, the soil may lose its ability to recover.  At the same time, the factors affecting soil resilience are primarily climate and management (burning, changes in plant composition, animal management, cultural labors and others).

Soil conservation is determined from its specific properties (organic matter content) and observation of its status (fertility). Processes related to compaction and loss of soil structures and organic matter, salinization and acidification are indicators of degradation (Kumar and Kafle 2009).

According to Amézquita et al. (2004), a good quality soil for the development of agriculture must have adequate water conductivity, so that it allows water to enter it and be easily redistributed in the volume of soil occupied by the roots. In addition, resistance to penetration should allow that pressure from the roots during their growth process be able to deform it so they can penetrate it, with a porosity of at least 50% with good distribution of macropores (18%), mesopores (25%) and micropores (12%) to ensure that water entrance, storage and residual humidity are good. It should also have adequate contents of all nutritional elements, with availability and good recycling. Among these features, organic matter content (4-5%) has great importance for its effect to balance physical, chemical and biological conditions.

A basic degraded soil loses nutrients for crop development and soil micro-fauna. In addition, one of the manifestations of its deterioration may be the decrease of its coverage. According to Quiros (2002), the loss of this indicator may cause output of about 124 kg N ha^-1, 1.03 kg P ha^-1, 23.91 kg K ha^-1, 31.94 kg Ca ha^-1 and 7.04 kg Mg ha^-1. While, with 90% coverage, the decrease of nutrients due to runoff is considerably less: 14.5 kg/ha of N; 0.12 kg/ha of P; 1.72 kg/ha of K; 2.56 kg/ha of Ca and 0.65 kg/ha of Mg.

Soil conservation in areas dedicated to cattle rearing has the objective of performing management practices that allow to stop degradation of this resource or recover its characteristics in a range that do not affect production and quality of grasses and forages. It should be based on the knowledge of the state of its properties, type of soil, pendant, grass, goal of its exploitation and cattle characteristics.  

The basic principles that allow soil conservation in areas dedicated to cattle rearing include soil utilization, according to agricultural aptitude, regionalization of grasses, use of technologies that are suitable for the edaphoclimatic potentialities of each system, use of legumes, silvopastoral systems, strategic fertilization, use of organic fertilizers, minimal labors for sowing and adequate animal management. It is also important to plant according to the level curves, maintain a high cover of the soil, use green manures, apply bio-fertilizers and bio-stimulants, and take into consideration those beneficial or effective microorganisms, among other elements that, integrating and combining them properly, favor the integrated management for soil conservation.

An appropriate management of situations associated to soil degradation should be supported by a sequential process of analysis of the problem (Lascano  2004, Lok et al. (2015): 

1. Problem diagnosis (identification of the type of degradation, effects of degradation and evaluation of ecological, social and economic impact of degradation)

3. Systematic follow up and control of the effect of technological responses applied through sustainability indicators

This analysis is particular for each agro-ecosystem. The efficiency of the process of soil improvement and conservation depends on the performance of this analysis.

In grasslands, integral evaluation of system functioning have to be conducted with the group of indicators from soil-plant-animal complex, which should be able of monitoring this functioning, and alert in time and indicate the best actions for a proper management.

It is foreseen the intensification of production due to the growing needs of world population, and as a response to climate change in agro-ecosystems where soil, as a biological base, should maintain its functioning in the new conditions and guarantee the required production.

Cattle activity is one of the major greenhouse effect gas releaser at a global level because it is the main source of CH₄ production (23 times better than CO₂, and doubled its atmospheric concentrations in the last years). Around 85 % of this methane is produced during the digestion process of productive animals. Additional 15 % of methane emissions from animal agriculture are produced by areas of untreated wastes, from animals in production. These areas are a source of water contamination. It is also important to consider that, in the terrestrial cycle of carbon, organic carbon of soil represents the best reserve in interaction with the atmosphere. Without any doubt, it is important the knowledge of processes and functions of soil that guarantee stability of carbon in the soil.

In front of these issues, livestock technologies are applied and monitored, which have demonstrated their efficiency for improving and preserving soil. These technologies allow to storage carbon in soil, being properly managed. Efficiency of some of them has been demonstrated:

• Silvopastoral based on Leucaena leucocephala in association with grasses for milk and meat production

• Association of grasses and mixture of creeping legumes for meat production

• Biomass banks with Pennisetum purpureum cv. Cuba CT-115

The evaluation of these technologies by Lok et al.(2015) to determine stored carbon, demonstrated that silvopastoral systems, mixture of legumes and biomass bank increased the carbon stored in the soil (CSS) with exploitation time. Single cropping decreased CSS and reached the lowest values among the evaluated technologies, which were between 60.4 and 43.7 t ha^-1.

The CSS, during the three years of evaluation and apart from technology, was between 43 and 65 t C ha^-1 and superior to reported facts (The International Bank for Reconstruction and Development and The World Bank 2007) as average for tropical regions. This source indicated that, generally, range between 35 and 40 t C ha^-1 from 0 to 30 cm of depth. The performance found should have been related to the characteristics of technologies because carbon from soil is stored as part of the organic matter  (Henderson et al. 2015), and the contents of organic matter and their dynamics depend, among other factors, on vegetation, its characteristics and management (Pellegrini et al. 2015). 

Developments in studies related to soil fertility show that there are opportunities of efficient management of this natural resource, and, besides the use livestock technologies, there are more cultural practices to improve its cover, biodiversity, resilience and fertility.

CHALLENGES OF SOIL SCIENCE IN AREAS DEDICATED TO CATTLE REARING

Currently, there are many challenges in places where climate changes are predominant and have direct implications on soil performance.

Soil studies have been characterized by the description of its state and consequent application of amendments that allow recovery of its productive potential. It was applied to correct the effects of fertility loss and not directly on causes, which are related to the decrease of dynamic balance needed by the soil to maintain its processes and functions.

For many years, agrochemical analyses were important for soil management. During the last decade, researches revealed that physical and biological indicators are essential in variability of cattle rearing systems mainly due to the effect of the animal component on the system and the role of edaphic biota on formation and structure of soil aggregates, nutrient availability, porous spaces, effective depth, apparent density, underground phytomass, carbon cycle and its storage in soil, among other factors.

During the last ten years, soil science related to the use of this resource in areas dedicated to cattle rearing, according to studies presented in international meetings and congresses, mainly worked on:

• Application of new sampling methods and  analytic techniques to evaluate fertility

• Improvement of the knowledge of recycling and nutrient mineralization processes, which determine the flow and storage of C, biogeochemical processes and mechanisms that guarantee sustainability of soil and water

• Integral management of fertilization through the application of organic and inorganic fertilizers, as well as bio-fertilizers

• Effect of different fertility management systems

• Sustainability indicators

• Biological fixation of N through the use of legumes in the systems

• Biodiversity studies, determination of edaphic biota associated to each system and its function in them

For example, in the 10th Congress of the Cuban Society of Soil Sciences (Instituto de Suelos 2015a), only 24.5 % of the presented papers belonged to cattle rearing results. Out of the discussed subject, there was a predominance of soil conservation and biology. This demonstrated that, currently, most of the studies are aimed to deepen on the knowledge of these subjects as an essential way of reaching sustainability and useful life of cattle rearing systems. There are still few efforts to dominate and know the soil in scientific researches, regarding the use of other agricultural systems, even though the total national agricultural area, the area dedicated to cattle rearing, has around 40%.

From the performed analysis and the current state of soil studies, knowing about its functioning and management actions to allow its restoration, together with the development of cattle rearing technologies with tested capacity for maintaining, recovering and preserving soil fertility and the implementation of new methods of strategic and integral fertilization, constitute important opportunities to reach an ecological management of soil and its recovery. To all these facts, it can be added the proper knowledge of forage and grass species with potential to adapt to different edaphoclimatic conditions, which allows the regionalization of grasses. The conscience-taking of decision-makers on the value of soil in cattle rearing systems and generation of systematic evaluation practice of its evolution should be taken into consideration.

a) Research and development should be focus on determining relationships among climatic and physical properties of soil and enzymatic activity of microorganisms (mineralization and C sequestration). In addition, the effect of good practices under different conditions, with the application of new technologies, should be analyzed. The effect of climate change on soil should be approached and work on achieving efficient methodologies that allow to evaluate its impact on soil. It is necessary to quantify and monitor the presence or absence of heavy metals in livestock residuals and identify new efficient management methods. It is also necessary to update the sampling techniques and soil analysis.  

b) Knowledge management and application of good soil management practices should be directed to generalization of knowledge in production areas, so an integrated management on agro-ecological basis could be achieved, which would encourage its resilience and guarantee sustainability. Training, support to producers and creation of reference scenarios are considered as essential. In addition, there must be an adequate flow of knowledge, which will generate, disseminate and share experiences of good research practices applicable to production. This process should ensure the involvement and problem awareness of decision-makers, which implies full social awareness and capacity building.

c) The policy and decision making should be directed to promote sustainable cattle rearing on the basis of improved production, environment conservation (soil) and cost reduction. All this will allow soil profitability and resilience. It is important to get a favorable environment by providing more support to small and medium producers, and implementing appropriate policies, with adequate infrastructure and credits and inputs to ensure the rights of land use. In addition, mechanisms should be created to motivate and encourage those that protect the ecosystems. It is necessary to ensure the extension and counseling service with a system of systematic and safe diffusion of knowledge. In this context, access to knowledge is considered essential.

For the realization of these challenges, it is essential the redefinition of soil management, which implies a change in its use and in the projection of its exploitation at small, medium and large scale. All this leads to consider it as a natural resource, slowly renewable and indispensable to human life.

The strategy for redefining soil management in grasslands also implies the conscious participation of society (producers, technicians, consultants, researchers, policy makers, and community) and planning and organizing the process from local level to basin level. It is important to encourage multifunctional soil use to promote synergies that favor appropriate economic, ecological and social exchanges and strengthen ecosystem services.

It is concluded that soils dedicated to cattle rearing have limiting factors and have lost their fertility, which increased in the last years with its consequent effect on productivity of cattle rearing systems. There are opportunities for proper soil management to be considered for recovery and conservation.

The redefinition soil management in grasslands should include research and development of science associated to these areas, appropriate knowledge management and application of good agro-ecological management practices, together with policies and decision-makings that promote and guarantee a sustainable development of this resource.

NOTE

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Received: 5/4/2016
Accepted: 4/7/2016

Sandra Lok Mejías, Instituto de Ciencia Animal, Apartado Postal 24, San José de las Lajas, Mayabeque, Cuba. Email: slok@ica.co.cu