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2019 Update: Nitrogen Inputs to Agricultural Soils from Livestock Manure, 1961-2017

Rome, 3 May 2019 - FAO releases today the 2019 update of the FAOSTAT Livestock Manure statistics. The FAO data facilitate analysis on the availability, distribution, use and loss to the environment of livestock manure, with regional and global trends, 1961-2017. The FAOSTAT data are analytical estimates, meant to provide a first starting point in support of analyses at national, regional and global level. They are compiled using official FAOSTAT livestock statistics and by applying the internationally approved methodologies of the of the Intergovernmental Panel on Climate Change (IPCC 2006 Guidelines). The data document the important role of livestock manure in soil applications for crop growth and yield, and can be usefully compared to similar data on the agricultural use of nitrogen in chemical and mineral fertilizers, also disseminated in FAOSTAT.

2019 Update Highlights

Global

  • Livestock manure provided over 115 million tonnes of nitrogen (Mt N) as input to agricultural soils in 2017;
  • Three quarters of livestock manure (88 Mt N) was left on permanent meadows and pastures, i.e., deposited by animals grazing on pasture, range and paddocks;
  •  One quarter (27 Mt N yr-1) was treated in manure management systems and applied as fertilizer;
  • About one third of all manure N deposited or applied to soils (34 Mt N out of the total 115 Mt N) was lost to leaching;
  • Cattle contributed over 50% of all livestock manure N;
  • Total livestock manure N inputs grew by 0.6% yr-1 from the previous year, compared to a mean growth of 0.9% yr-1 over the previous ten-year period 2008-2017.
  • The overall mean historical growth rate, i.e., over the period 1961-2017, was of 1.3% yr-1. Livestock manure inputs were 75% greater in 2017 than in 1961.

Regional

  •  In 2017, the largest share of total livestock manure N inputs were in Asia (35%) and Africa (25%), followed by South America (16%), Europe (10%), North America and Oceania (4%). This can be compared to shares in 1961, where the largest inputs were in Europe and Asia (25-26%), followed by Africa and South America (14%), Oceania and North America (8-9%).
  • Over the ten-year period 2008-2017, total livestock manure N inputs grew significantly in Africa (+3.1% yr-1) and Asia (1.1% yr-1), more slowly in South America (0.2% yr-1), while decreasing in Oceania (-0.6% yr-1), Europe and North America (-0.3% yr-1). These figures can be usefully compared to the mean historical growth rates observed over the period 1961-2017, for Africa (+3.9% yr-1), Asia (2.6% yr-1), Europe (-0.3% yr-1) and Oceania (-0.4% yr-1), North America (0.2% yr-1) and South America (1.1% yr-1).  

 Country

  • In 2017, the highest N inputs on pasture by country and animal type were recorded in Brazil (7.9 Mt N from beef cattle), the United States of America (3.0 Mt N from beef cattle) and China (2.0 Mt N from goats).
  • The highest inputs from manure treated and applied to soils by country and animal type were largest in China (1.4 Mt N from swine), India (1.0 Mt N from buffalo), and again China (0.9 Mt N from chicken).

Global Overview

Statistics on the use of synthetic (i.e., mineral and chemical) and organic fertilizers are crucial for identifying current practices and trends in soil N inputs and to inform planning and policies towards the design and implementation of more sustainable agricultural systems (FAO, 2017). The indicators in the FAOSTAT domain “Livestock Manure” provide estimates of nitrogen (N) inputs to agricultural soils from livestock manure and of the losses occurring through leaching and volatilization. Estimates are computed and disseminated by livestock type, by country and in regional aggregates, for the period 1961–2017. Estimates use official FAOSTAT statistics of animal stocks as input and apply N excretion and other coefficients characterizing the Tier 1 approach of the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National GHG Inventories (IPCC, 2006).  The full methodology is described in the online metadata sheets of the FAOSTAT Livestock Manure domain, as well as in the FAO report on livestock manure statistics (FAO, 2017).

Availability and use of organic fertilizers, largely sourced from livestock manure, parallels over time the significant increases in livestock populations that have accompanied agricultural development around the world. Besides macro and micro-nutrients, manure also provides organic matter to agricultural soils – a key determinant of soil health. However, inappropriate manure management and excessive applications can also have detrimental effects on the environment, contributing to the contamination of water and soil resources and to high greenhouse gas (GHG) emissions. Efficient nutrient management plans and strategies are needed to maximize crop productivity while minimizing the potential environmental impact due to the high amount of nutrients being applied today.

In a simplified cycle of the livestock manure, the organic nitrogen that is excreted from animals is either deposited directly on pastures during grazing, or it is collected, stored and processed across a range of manure management systems. Treated manure is subsequently available for application to agricultural soils, mostly cropland.

At global level, FAOSTAT statistics indicate that currently, of the total of 115 Mt N in 2017, the largest share of manure (87 Mt N ) was left on permanent meadows and pastured by grazing animals (i.e., on pasture, range and paddocks). Another 27 Mt N yr-1 were applied to agricultural soils after treatment in manure management systems. Global trends of these separate N inputs to agricultural soils are illustrated in Chart 1, showing the absolute contributions of livestock manure and synthetic fertilizers, for comparison.Total livestock manure N inputs grew by 0.6% yr-1 from the previous year, compared to a mean growth of 0.9% yr-1 over the previous ten-year period 2008-2017. The overall mean historical growth rate, i.e., over the period 1961-2017, was of 1.3% yr-1. Livestock manure inputs were 75% greater in 2017 than in 1961, when total inputs were only 66 Mt N.

Regional OverviewThe growing nitrogen inputs from livestock manure are driven by the observed increase in animal numbers worldwide. Since 1961, the N contribution from all livestock manure has grown more than threefold in Africa (from 9 to 29 Mt N), more than twofold in Asia (from 16 to 40 Mt N) and approximately by 70% in the Americas (from 17 to 29 Mt N). By contrast, N inputs from livestock manure decreased in Europe by 35% (from 17 to 11 Mt N yr-1), mostly since the early ‘90s and in relation to regulation limiting N pollution from agriculture. In addition, Europe is the only region where the amount of N treated and applied to soils is larger than the amounts left on pasture by grazing animals, indicating, compared to other regions, a preponderance of intensive, localized production systems over extensive system with grazing. When properly managed, organic N from livestock manure represents an environmentally friendly source of nitrogen that may be used instead of synthetic fertilizer nitrogen.

The relative contributions of livestock manure and synthetic N sources have in fact changed during the past decades. FAOSTAT statistics illustrate the average regional trends in both the organic and chemical sources of N inputs (Chart 2). In Africa, in the most recent decades the nitrogen contribution from livestock manure on agricultural soils was still about eight times larger than contributions from synthetic fertilizers (26 and 3.5 Mt N, respectively). In Asia, synthetic fertilizer N applied to soils were almost twice the inputs from livestock manure in the current decade, with this gap growing over time. In Europe, nitrogen applications from livestock manure were similar to those from synthetic fertilizers in Europe in the 1990’s (each source being about 14 Mt N). Since then, inputs to agricultural soils from synthetic fertilizers remained the same while those from livestock manure were reduced by about 20%. As a result, application of synthetic fertilizers on agricultural soils in Europe are greater than from livestock manure.

Countries

FAOSTAT estimates of nitrogen inputs from livestock manure are based on statistics of livestock numbers. Between 2000 and 2017, Brazil and China were the countries with the largest N inputs from livestock manure left on pasture (8.6 and 7.4 Mt N yr-1, respectively). In Brazil, the largest contribution (more than 80%) was from beef cattle. By contrast, in China, manure N inputs from small ruminants and particularly goats, were the dominant manure N source (25%). China had the largest amounts of N inputs from livestock manure applied to soils (4.8 Mt N yr-1), followed by the United States of America (2.4 Mt N yr-1). Livestock manure from swine contributed 20% to the total treated and applied to soils in China, whereas in the USA chickens manure was the largest source (21%).

Explanatory Notes

The FAOSTAT domain Livestock Manure presents information on the availability of livestock manure N for applications to agricultural soils and on the N losses that occur from manure management systems. These estimates are also used as an input to calculate greenhouse gas (GHG) emissions from agriculture, which are disseminated in the FAOSTAT domains “Manure Management”; “Manure left on pasture”; and “Manure applied to soils”.

References

FAO, 2017. Nitrogen inputs to agricultural soils from livestock manure: new statistics. Integrated Crop Management, vol. 27–2017. Food and Agriculture Organization of the United Nations, Rome, 2017.

IPCC, 2006. 2006 Guidelines for National GHG Inventories, Vol. 4. Agriculture, Forestry and Other Land Use. IPCC, Geneva, Switzerland.

Figure 1. Global N inputs to agricultural soils from livestock manure and synthetic fertilizers (1961–2017)
Figure 2. Comparison of regional average N inputs from livestock manure and synthetic fertilizers in 1992–2001 and 2008–2017