The UN Environment Programme just released the Year Book 2014 emerging issues update, a special e-book edition ten years after the first Year Book in the series. The 2014 Year Book presents ten environmental issues of the last decade, and highlights the challenges and solutions related to each one. Three of the emerging environmental problems are particularly relevant to conservation agriculture and demonstrate the important role that CA can play in modern agriculture.
Chapter 1: Excess Nitrogen in the Environment
The global nitrogen cycle has been greatly modified due to the excessive use of inorganic nitrogen. The amount of usable nitrogen created by humans is now greater than the amount produced through natural processes, and nitrogen is overloading natural systems. Excess nitrogen negatively contributes to ecosystem services, air and water pollution, global climate change, coastal dead zones, and biodiversity loss. Practices of inefficient and over-application of nitrogen in agriculture are responsible for much of global nitrogen pollution. The chapter focuses on the increased coastal dead zones and climate change impacts caused by excess nitrogen. Dead zones, which occur when fertilizer run-off creates algal blooms, have doubled in each of the last four decades. Nitrous oxide (N20) emission are increasing globally. N20 is 300 times more effective at trapping heat than carbon dioxide, making it a powerful greenhouse gas.
“More than two-thirds of atmospheric emissions of nitrous oxide arise from process in soils, largely resulting from the application of nitrogen fertilizers.”
Any effective climate change mitigation will focus on the reduction of nitrous oxide emissions.
Conservation agriculture practices greatly reduce nitrogen losses through soil runoff. Soil nutrient supplies and cycling are enhanced by the biochemical decomposition of organic crop residues at the soil surface. This reduces nitrogen leaching through both the air and water. Soil fertility is built up over time under conservation agriculture, so fewer fertilizer amendments are required to achieve optimal yields. This is especially true for nitrogen, because the use of leguminous cover crops can satisfy much of the nitrogen needs of primary food crops. All of these soil management practices directly improve plant nitrogen uptake, significantly reduce the amount of inorganic nitrogen fertilizer applied, and consequently minimize excess nitrogen pollution.
Chapter 6: Realizing the Potential of Citizen Science
Citizen science is when people who are not professional scientists participate in any of the following: collection and analysis of data, development of technology, testing of natural phenomena and dissemination of the results of activities. Citizen science raises awareness, informs policy decisions, widens researchers perspectives, and makes science more relevant to the world’s problems.
Conservation agriculture has been taking advantage of citizen science since its conceptualization. Farmers and farmer associations pioneered CA systems. A participatory approach to local adaptation of CA principles is often used in its promotion. This approach has achieved success throughout Latin America and is beginning to reap rewards in Africa. Global progress of CA has relied on the innovation of farmers for development of new direct-seeding equipment, cover crops, and pest/weed management strategies.
Chapter 9: Securing Soil Carbon Benefits
Soil carbon is crucial for maintaining the world’s climate and ecosystem services. Agricultural intensification is the main source of the soil carbon losses in the last 25-years that have reduced the agricultural productivity of 25% of global land area. Besides reducing soil fertility, carbon losses accelerate global climate change.
Improved land management is vital for reducing soil carbon losses. Soil carbon loss is associated with tillage, which causes soil aeration and soil aggregate destruction that increases the decomposition of soil organic carbon. Consequently, tillage reduces organic matter of intensively cultivated soils and contributes to C02 emissions. The chapter specifically mentions conservation agriculture as an effective methodology to increase carbon inputs to agricultural soils and reduce carbon losses, and directs readers to a link on CA in Malawi and Zambia. The three principles of CA help to keep the positive balance between carbon input and carbon outputs. Keeping crop residue on soil builds soil carbon stocks, while minimum soil disturbance and permanent soil cover reduces soil carbon loss to the atmosphere. The extent that CA can increase soil carbon sequestration depends on soil type and climate.
Conservation agriculture, like any agricultural methodology, must be adapted to local environmental and socio-economic conditions. It is not a silver bullet solution to the problems facing modern agriculture, but it is one of the better alternatives available. With growing urgency to address issues like nitrogen overloads and soil carbon loss, CA emerges at the forefront of international agriculture policy and research.