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Agroecology and Soil Health

Hanna Weber's picture

Dear TECA members,

We would like to invite you to participate in our discussion on “Agroecology and Soil Health” with the objective to identify successful site-specific agroecological farming practices which improve soil health.

The design of diverse agroecological systems can significantly improve soil health and reverse soil degradation while increasing the production of nutritious food. These systems build on ecological principles and are based on system diversity and ecological synergies.

Soil health is at the core of agroecology. This approach recognizes the equal importance of the physical, chemical and biological soil health adapting specific practices to specific ecological conditions in order to increase soil organic matter, recycle nutrients and maintain soil biodiversity.

This upcoming discussion is to follow-up with our previous discussion on “Sustainable Farming through Agroecology”.

We encourage individual farmers, farmer’s organizations, extension services, NGOs, researchers and every individual interested in agroecology to participate in the upcoming discussions and share your ideas and practices which have given positive results.

The discussion will take place from 20-Feb-2017 to 12-Mar-2017 and address the following questions:

  1. How do you assess soil health in the field?
  2. What are agro-ecological practices contributing to the improvement of soil health?
  3. What are the benefits experienced by farmers in applying these kind of practices?
  4. Where are the constraints of these practices?
  5. What are the challenges farmers face on the field with regards to soil?

We are happy to introduce our expert who will be able to answer your questions and share their experiences with us.

  • Dylan Warren Raffa, Sustainable Soil Management, FAO
  • Marjon Fredrix, Soil Health Management, Farmer Field Schools, FAO
  • Dominique Masse, Functional Ecology & Biochemistry of Soils & Agro-Ecosystems (UMR Eco&Sols), Ecological Intensification of Culitivated Soils in West Africa (LMI IESOL) 

We are looking forward for your contributions and a fruitful discussion!

Hanna & Prachi

TECA Team

Comments

Soils are the basis for food production and mediate essential ecosystem services.

However soils are characterized by a high potential for rapid degradation and very slow formation and regeneration processes. For too long soils have been considered as a lifeless substrate in which to grow food by topping them up with water and nutrients which has resulted in about a third of our soils today being moderately to highly degraded. Currently about 12 million hectares of tops soils are lost every year indicating that we have about 60 years of top soils left. Guaranteeing nutritious food and ecosystem stability for the future generation is therefore rooted in the sustainable management of soils.

FAO refers to soil health as “the capacity of soil to function as a living system. Healthy soils maintain a diverse community of soil organisms that help to control plant disease, insect and weed pests, form beneficial symbiotic associations with plant roots, recycle essential plant nutrients, improve soil structure with positive effects for soil water and nutrient holding capacity, and ultimately improve crop production. A healthy soil also contributes to mitigating climate change by maintaining or increasing its carbon content”.

The agroecological approach for healthy soils starts by restoring soil life in order to re-establish and/or enhance the multiple soil-based biological processes. This requires:

Increasing and monitoring soil organic matter:

·         Soil organic matter is considered the most common deficiency in degraded soils. Thus, it is considered/used as the main indicator for soil quality. Practical, accessible indicators can support local decisions and larger landscape monitoring and analyses for district level implementation.

Facilitating and monitoring of soil biodiversity:

·         Soil biological communities are directly responsible for multiple ecosystem functions and they can also be used as an indicator for soil health

Build on local farmers’ knowledge:

·         Participatory scientific approaches to soil ecosystem management, such as Farmer Field Schools, are of great importance to inform farmers’ knowledge with researchers’ scientific principles in order to better locally adapt agroecological systems.

The soil is a complex system build on a mineral matrix that contain water, organic matter and nutrients more or less linked to the matrix, and that provide a habitat for divers microbial and faunal organisms or belowground parts of the plants. All these components are not static and are under multiple physical and biochemical interactions that determine at any time the status of these different components in term of quantity or of quality. Soil is not a passive substrate but it is continuously dynamic under the pressure coming from its external environment or from anthropic activities. All these internal and external interactions or feedback will determine the soil fertility or in other word the ability of soil to support and sustain plant growth, but also soil ecosystems services. Climate and human activities changes led to a strong degradation of soil fertility and even the disappearance in fine of a human civilization.

Agro-ecology is based on the intensification of ecological processes. Concerning soil, research should focus on ecological functioning and biological interactions, and how to enhance soil ecosystem services through ecological processes. The challenge is to develop models where biological life in soil and interactions among all soil components are represented as the motor of soil functioning.

Agro-ecological practices mostly target family farms and explore local dimensions of agricultural activities. Looping nutrients cycles at the farm, village or small regional scale is an objective to drastically reduce farmers’ dependence on external inputs. But, organic resources recycling and associated nutrient at the scale of the aggregate to the scale of the landscape is a major issue that will determine soil fertility and productivity as soil health. So the challenge to assess the soil health will be also to associate to the soil per se observations other components of agricultural ecosystems: field plants, farm/village organisation and landscape structure. More interactions between models developed at different scales are required. For instance, the productivity of the agro-sylvo-pastoral systems in West Africa is clearly determined by the ring organisation. Compound fields receive large amount of organic matter and nutrients coming from other part of the village (bush fields, no cultivated zones as savannah or lowlands). In this system, livestock acting as fertility transfer vector or trees of the parklands are essential. The soil health at a local point will largely depend not only to the farmer practices at the scale of the fields but also to the natural resources management at the village scale and even beyond at the territory scale.

The question will be also to capitalise on local knowledge. Farmers have strong knowledge of their soils. For instance, while farmers perceive that their soil is degraded, soil analyses may show very little change. Soils scientists have to consider this local knowledge that could help to formulate hypotheses on soil functioning that will determine soil fertility but also soil health. Another challenge will be to set up an integrated, systems-oriented, trans-disciplinary approach. This co-construction is essential if more sustainable pathways to soil health are to be created.

Agricultural soil scientists have also to be concerned by the soil functioning in natural formation. One issue of ecological engineering is to mimic the nature. Natural formation is rich of process conferring ecosystem resilience face to disturbance. For instance, the concept of organic matter and nutrients resources concentration observed at the scale of savannah agrosystems in West Africa could be observed in savannah. Under trees or some perennial herbaceous as Andropogon gayanus have the capacity to concentrate nutrients and initiate a permanent loop of nutrient that guarantee the plant productivity and survival. The role of soil engineers as termites which create soil fertility hotspot. The objective will be not to reproduce strictly these systems in cultivated area but to learn from these “natural” principles to analyse some farmers practices and to innovate in soil management practices.

Soil organic matter has a key role in the overall behaviour of soils and agroecosystems: resistance to soil erosion, soil water retention, soil fertility for plants and soil biodiversity. Sufficient amount of organic matter is one of the main indicator of the health of soils. That is why agroecology promotes organic carbon-rich soils. In the same time even small changes of the soil carbon pool have tremendous effects on greenhouse gas balance. Thus maintaining organic carbon-rich or increasing the soil carbon soils in agricultural lands contribute not only to ensuring food security but also to stabilising the climate. Farming practices that boost the amount of organic matter in soils exist and are currently adopt in tropical areas. Three videos in Madagascar, Togo and Senegal illustrate different farming practices (organic amendments, plant associations) that improve or maintain soil C stocks. The objectives of the videos are also to show the collaboration between research, non-government organizations and the local population to manage organic matter inputs into soils to maintain their productivity.

The videos are gathered here: https://www.youtube.com/playlist?list=PL5g1L2-mjc3RN6YU1vb92DDYu5cmeRaWc

1.     Food security and climate change. Farmers in Madagascar adopt agro-ecological practices https://youtu.be/C_ydvspJcbQ

2.     Food security, agroecology and climate change. Farmers in northern Togo take action https://youtu.be/UfbWhk9NH7k

3.     Food security and agroecology. Integrated crop-livestock farming for maintaining crop diversity In Senegal. https://youtu.be/urgNDsRQy7Y

(from Dr. Tiphaine Chevallier, IRD, Eco&Sols)

Prachi Sharma's picture

Dear Eric,

Thank you very much for sharing these agroecological practices. It is very nice to hear the testimony of the farmers on how such practices help the environment as well as the farmers and how the collaboration between the research organizations, NGOs and the local population is necessary for implementation of these practices. 

 

If one considers that soil health and soil quality are synonymous – considering that scientific literature often links soil health with biological properties – one can define soil health/quality as the capacity of soils to deliver ecosystem (or agrosystem) services.

Growing awareness and evidence that soil biodiversity is inextricably linked to the provision of ecosystem and agrosystem services and that a new paradigm is occurring in agriculture, imposes on scientists and stakeholders to work together on defining and designing of innovative cropping systems that better take into account the belowground biodiversity and soil ecological processes. The need to assess and monitor soil health and to understand intimate relationships between plants and belowground organisms are critical to develop agroecological, sustainable practices in order to increase agricultural productivity.

Different tools are developed in order to assess soil health, and especially ecological soil functions linked to soil biodiversity. Following Kibblewhite et al. (2008, Phil. Trans. R. Soc. B, 363 : 685-701), biotic activities interactions between functional groups of soil biota regulate four aggregated main ecological soil functions, i.e. carbon transformations, nutrient cycling, soil structure maintenance, and pest/biological population regulation which are at the base of ecosystem and agrosystem services.

Different indicators (or proxys) are being developed by scientists and/or available in the literature to assess soil biodiversity and related ecological functions. These indicators may be more or less complex (sometimes necessitating specific equipment, and specific skills), more or less cheap, more or less technical. For instance, the description of soil nematode communities is a very good indicator of soil health but requires scientific skills.

Classical indicators deal either with soil biota communities or with functions. Classically there are a lot of papers on soil microorganisms, nematodes, macrofauna, and earthworms in agricultural systems generally showing higher abundance, biomass, diversity in agroecological systems, i.e. systems with no or superficial tillage, with organic inputs, with plant associations and rotations, absence of pesticides. Regarding ecological functions, some indicators allow the assessment of the function of C transformation, such as the Bait lamina test (Römbke, 2014, Plant and Soil 383:43–46), the tea bag index (Keuskamp et al., 2013, Methods in Ecology and Evolution 4:1070–1075), the litterbag method (Verhoef, 1995, Academic Press, London). Other indicators assess nutrient cycling, e.g. nutrient availability, respiration of soil organic matter. Changes in soil structure can be assessed through simple aggregate stability measurement or Beerkan test. At last, regulation of pest populations can be assessed through the analysis of pest communities (either nematodes, or white grubs) or the effect on plant growth.

Such indicators are developed and used by Eco&Sols team (http://www.umr-ecosols.fr) and partners in Madagascar, West Africa and South-eastern Asia with the aim to combine diverse indicators to globally assess soil health and to propose an ecological performance value of agrosystems. Recent studies in Madagascar have shown the great interest of such an approach to assess soil health.

E. Blanchart, A. Brauman, J. Trap (IRD, Eco&Sols, Montpellier, France)

Luo Shiming's picture

There are many  agroecology practices which are good for soil health in China. 

 Rotation systems of double rice crop with winter green manure (milk vetch), with winter nitrogen fixing fern Azolla, and with winter potato are good for soil health as well as for increasing rice yield. 

Rice co-culture systems with duck or with fish are  widely accepted practices to reduce chemical input and improve nutrition intake in many mountainous area.

The use of biogas tank to digest animal waste and recycling the liquid part and solid part to rice field is an effective way to link plant production with animal production. It also provides energy for farmers in the village while helps to improve soil fertility. 

Images: 
Hanna Weber's picture

Dear Luo Shiming,

thank you for sharing three agroecological practices on rice production with us. Regarding the rice-duck system I’d like to share with you the link for a technology practiced in Philippines which is already published on TECA: http://teca.fao.org/read/7724. Apart from reducing the amount of chemical inputs, do farmers also experience other benefits or any difficulties with this practice? Thank you very much!

Kind regards,

Hanna

Luo Shiming's picture

Dear Hanna,

  The practice of duck-rice in China is quite simular to the practice in the Philippines.

   There are more benefits the farmer can get from rice-duck co-culture besides the  reduction of chemical fertilizer. They can  also reduce the use of chemical pesticides because of the activity of duck. According to our research, duck can reduce the high of rice, hence can reduce the lodging rate of rice. It can also reduce green house gas emission. Because of the income from duck, farmers can get higher total income from this system.

  There are some difficulties which farmers have to overcome. They have to learn how to choose a suitable duck species (local small body size), to learn the releasing density of duck (250-300 /ha), to learn the construction of fence to prevent the escape of duck and even distribution of duck in field, to learn the control of possible natural enemies of duck such as wessel,  to learn the feeding rate (not too much), and to learn the new fertilization method (reducing rate, and change of the time of topdressing) etc. 

  So, it is good to have a training before the practices or to have a demonstration farm nearby first.

  Thank you for your common!

 Luo Shiming

Application of green manure to soils has been considered as a sustainable method of production. incorporating green manure in the soil increases soil carbon and organic matter and as such increases plant nutrient availability and uptake. evidence show that application of green manure can suppress soilborne diseases. it is, therefore, important that a production system that is employed should be able to provide multifold functions like green manure do.  

Prachi Sharma's picture

Dear participants,

I would like to share with you all a case study from Vietnam on IPM. 

Using agroecological principles such as minimum tillage and integrated pest management (IPM), farmers are able to grow potatoes in lowland rice production systems with increased incomes. After harvesting, rice fields are drained using drainage furrows which result in raised beds and potatoes are grown on these beds covered with rice straw as mulch.

This practice is labour-saving and has been applied by several farmers in Vietnam. The additional benefits of this practice include increased income a substantial reduction in the amount of irrigation and the use of fertilizers and pesticides. This technology also contributes to reducing the emission of greenhouse gases by using the leftover rice straw as mulch (instead of burning it). 

Do you have similar experiences to share with us?

 

Please refer to the attached file for more details of this practice.

Attached files: 

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