Nitrogen and Sulfur

The Nitrogen Group

The COMIFER Nitrogen Group gathers a few hundred registered members, of whom about thirty regularly attend meetings. Members are interested in the nitrogen problem that presents itself in various sensibilities: deciphering the mechanisms explaining the flow of nitrogen in the soil-plant-atmosphere system, application of environmental approaches and prescription of nitrogen fertilization.

Therefore, members come from very different backgrounds: Research (INRA GEMAGREF), Institutes, Agro-distribution, Ministries of Agriculture and Environment, Water Agencies, Fertilizer Industry, Education …

The group meets 2-3 times a year in plenary sessions and 2 to 3 times in small ad-hoc groups to discuss certain themes.

The main themes over the past decade:

• The 90s were very focused on reflection on the implementation of the European directive on nitrates, a number of members of the Nitrogen Group participated in working groups initiated at the time by the CORPEN.
• In the mid-90s, the Nitrogen Group drafted the methodological guide for the calculation of nitrogen fertilization of annual crops, at the request of CORPEN.

More recently, the topics have returned to understanding the explanatory mechanisms of nitrogen flow:

• Gaseous losses at the expense of mineral and organic fertilizers and soil: work on ammonia volatilization from manure INRA Rennes, CEMAGREF Rennes, work on measuring the volatilization through direct (micrometeorology) and indirect channels ( assessment of defects isotope tracing) INRA Versailles, Grignon and Laon-Reims, work on denitrification INRA Dijon.
• Microbial immobilization of nitrogen in the soil under crops: works on isotopic tracing by INRA Laon with the collaboration of CRA Lorraine.
• Effects of temporary nitrogen deficiency on wheat: INRA Grignon.
• Searching for a better nitrogen efficiency of fertilizers by reducing the competition between crops, gaseous losses and microbial immobilization: CRA Lorraine offers a calculation and fractionation method for the nitrogen fertilization of corn.
• Searching for a better adaptation of nitrogen rates on grain by the use of nitrogen fertilization management tools: ARVALIS, INVIVO, YARA, GPN.
• Summary of work on the nitrogen fertilization of rape: Sustainability of nitrogen fertilization and the role of winter rape in the environmental management of crop rotation: CETIOM, INRA Grignon INRA Reims, ESA Lille.
• Nitrogen and precision agriculture: Contribution of ARVALIS, INRA Avignon, presentation of operational tools or in preparation Hydro N-Sensor, Satellite Pictures.
• Nitrogen Law: presentation of project on nitrogen surplus fees: Ministry of Environment.
• Presentation of the STICS model to simulate the dynamics of water, carbon and nitrogen in the soil-plant system. : INRA Laon.

Topics to be covered in future meetings:

 For information on the Nitrogen Group, please contact the group leader: Marc HERVÉ (Eurochemagro)

The Sulfur Group

In a dormant state for the past few years, the “Sulfur” Group was merged with the Nitrogen group.

Initially, two lines of work were retained:

1. The state of the sulfuric (nutrient element) balance in France
2. Inventory of recommendations in matters of sulfur fertilization

In the longer term, the group plans to address the analytical methods of sulfur dosing and diagnostic tools of the sulfur nutrition of the crops.

Sulfur balance sheet items at the national level

Inputs:

• Inputs from mineral fertilizers: thanks to the statistical compilation by UNIFA we know that in 2002-03 the contribution of SO₃ was 474,369 t (excluding sulfur magnesium fertilizer) for a total estimate of about 560,000 t SO₃. These contributions have declined from 1998 to 2001, to recently go up slightly. As for the structure of this consumption, it is noted that if compound fertilizers contribute half, sulfur nitrogen were strengthened over time at the expense of sulfur inputs from phosphate fertilizers. Regionally these sulfur inputs decreased, especially in the livestock and mixed farming areas (Brittany, Pays de Loire).
• Contributions by manure: while the sulfur mineral fertilizer is in the form of sulfate, thus directly assimilated, that of manure is in mineral form for only a very small proportion. Most of the sulfur of animal waste is in organic forms, whose bioavailability is minimal over the year (annual mineralization 1 to 3% of the organic sulfur according to Danish work). In any event, estimating this source “animal waste” results in about 325,000 t SO₃ Regionally this source does not have a high incidence, with the exception of in Britain mainly.
• Atmospheric fallout: 14 kg SO₃ / ha / year of deposition in 1997, suggesting a figure of around 10-11 kg today
• No information on contributions by residues of the food industry, sewage sludge and irrigation water

Outputs:

• Exports by crops: using the methodology of the FNIE-The Sulfur Institute study, 1982-83, one estimates SO₃ 955946 t for 2003 or 10% more than 20 years ago (better yields for rapeseed)
• Leaching: a highly variable position that ranges from a few tens of kg to 340 kg SO₃ / ha / year depending on rainfall and soil type. An annual estimate of total losses at the national level is impossible.

This balance approach suggests that in large growing areas total sulfur requirements, especially in years of strong returns, are not fully covered. However, it should be refined at the regional level, knowing that the results are particularly relevant at the farm and for the most sulfur demanding crops.

The State of Current recommendations:

It seems they are for rapeseed and straw cereals, which is logical given the importance of sulfur nutrition for these crops.

• Rape: the CETIOM recommendation of 75 kg / ha SO₃ established 15 years ago is widely followed by their annual survey. However 25% of rapeseed surfaces do not receive any sulfur input. No recommendation as to the type of sulfur fertilizer by CETIOM.
• Soft wheat and winter barley: Arvalis published (in April 2003) an updated grid. According to 3 criteria (soil, rainfall from October to February, and previous sulfur intake) it advocates from 0 to 40 kg / ha SO₃ with a preference for sulfur nitrogen. No survey to determine the actual practices of grain farmers.
• No data on fodder crops, which are nevertheless consuming significant amount of sulfur.

Fertilizer producers and distributors offer a wide array of fertilizers containing sulfur: Commercial buyers take advantage of off-season purchases from distributors.

Download the presentation:
Sulfur and crop fertilization

For information regarding the sulfur group, please contact the facilitator Olivier GOUJARD (K+S KALI FRANCE).