What's new in thinking about the futures of AR4D?

What's new in thinking about the futures of AR4D? The futures of phosphorus and nitrogen: a reason to think again about agronomy?

Johan Rockström, Will Steffen and a team of eminent scientists have just published an update of their research on planetary boundaries1. The results are unequivocal. Four of the nine boundaries have now been crossed or are about to be crossed: climate change, biodiversity loss, rapid landsystem change, and altered nitrogen and phosphorus cycles. These boundaries are nevertheless defined as thresholds which, if transgressed, could drive the Earth system into a new state, one that would undoubtedly be far less favorable to the development of human societies. Today, most of the phosphorus rocks are in Morocco, China and the USA and 90% of all production is used in agriculture. About 50% of the excess nitrogen and phosphorus is concentrated in only 24% and 21% of the world’s cropland area, respectively, while many countries do not have the physical reserves or the economic means to meet their needs in mineral fertilizers. China, India, and the United States together account for about 64 to 66% of excess nitrogen and phosphorus (articles 1 and 3). The efficiency of nutrient use is very low2. At global scale, trade of agricultural products improves phosphorus resource use efficiency but at regional scale, current phosphorus management in agroecosystems exhibits major imbalances (presentation 2). These imbalances are often due to crop and livestock segregation which drives major P flows and P resource displacement. Too much phosphorus have negative environmental and health impacts (article 4) but, in the use of phosphorus, there are ways to target the crop more and the soil less (article 5). The production and use of nitrogen leads to increased GHG, but the nitrogen losses are still high (see footnote 2) and with considerable environmental cost. “Only 47% of the reactive nitrogen added globally onto cropland is converted into harvested products, compared to 68% in the early 1960s, while synthetic N fertilizer input increased by a factor of 9 over the same period. This means that more than half the nitrogen used for crop fertilization is currently lost into the environment” (articles 6 and 7). It seems that these very costly - for human health and for the environment - practices call for a renewed agronomic research (article 8 to 10). Marie de Lattre-Gasquet, Hervé Saint Macary and Thierry Brunelle

1

www.sciencemag.org/content/early/2015/01/14/science.1259855 cited by La lettre de l’IDDRI, January 2015, No. 56. 2 According to the report “Our Nutrient World” (http://www.initrogen.org/sites/default/files/documents/files/ONW.pdf), considering the full chain, on average over 80% of N and 25%-75% of P consumed (where not temporarily stored in agricultural soils) end up lost to the environment.

CGIAR Consortium Office and Cirad – Foresight brief 8 – January 2015

Page 1

Phosphorus3 In 2014, three conferences on phosphorus were held: “Séminaire phosphore” organized by IRSTEA http://phosph-or2014.irstea.fr/presentations/ “Phosphorus in soils and plants” http://psp5-2014.cirad.fr/ and “Sustainable Phosphorus Summit” http://sps2014.cirad.fr/programme They were many interesting presentations. We have picked two of them. Article 1: In the article “Leverage points for improving global food security and the environment”, Paul West and his colleagues have found that “~50% of the excess nitrogen and phosphorus is concentrated in only 24% and 21% of the world’s cropland area, respectively. China, India, and the United States together account for ~64 to 66% of excess nitrogen and phosphorus. Furthermore, rice, wheat, and maize alone are responsible for ~58 to 60% of the excess nitrogen and phosphorous of the 17 crops we analyzed globally.” Using a yieldresponse model, they estimated “that nitrogen and phosphorus applied to wheat, rice, and maize could be reduced by 14 to 29% and 13 to 22%, respectively, while maintaining current yields. Targeting reductions in fertilizer use to a small set of crops and countries could therefore have a large effect on global nitrogen and phosphorus pollution. Further efficiency gains are possible by altering the timing, placement, and type of fertilizer”.

Presentation 2: Thomas Nesme and Elena Bennett presented Sustainable phosphorus use in agroecosystems: A story of global imbalance and resource recycling. They look at the flows of phosphorus and show, for example, that international P flows are driven by soybean and cereals. They propose a strategy with five elements to adapt to the different phosphorus contexts.

3

The idea for this theme came from an article in http://veilleagri.hautetfort.com/archive/2014/09/17/de-nouveauxtravaux-sur-la-dependance-de-l-agriculture-au-ph-5449096.html


Page 2

Presentation 3: “Trends of phosphorus use efficiency in the food chain of China” made by Lin Ma and his colleagues at the 5th Phosphorus in Soils and Plants Symposium (Montpellier, September 2014), questions the efficiency of phosphorus use in China. Phosphorus input was 5 times larger in 2005 than in 1980. It is leading to a dramatic increase in the cost of food due to low Phosphorus Use Efficiency (PUE) and high Phosphorus losses. To improve the situation, the authors recommend improving diets (animal and crops food consumption go far beyond Chinese food dietary guidelines), and implementing an integrated nutrient management systems that would decrease Phosphorus losses, and would greatly increase PUE in the whole food chain. P flux increased dramatically in the food chain of China P flow （10000 ton）

1600 1400 1200

Household Food processing Animal production Cropland production

1000

800 600 400

200 0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 Year (Ma et al., Unpublished data)

Article 4: Public health impact of dietary phosphorus excess on bone and cardiovascular health in the general population by Mona S Calvo and Jaime Uribarri points out the negative health impacts of excesss phosphorus in nutrition. Adverse health effects are beginning to emerge in individuals with normal renal function, which questions the safety of the high cumulative use of phosphate ingredients in processed and prepared foods. Thus, the article explores the potential adverse impact of the increasing phosphorus content in the American diet on renal, cardiovascular, and bone health of the general population. Increasingly, studies show that phosphorus intakes in excess of the nutrient needs of a healthy population may significantly disrupt the hormonal regulation of phosphate, calcium, and vitamin D, which contributes to disordered mineral metabolism, vascular calcification, impaired kidney function, and bone loss.

Article 5: A team of British researchers proposes to “Feed the crop not the soil: rethinking phosphorus management in the food chain”. They recommend to target the crop more and the soil less which requires that crop Phosphorus demand and soil Phosphorus supply must be considered separately, and the difference made up with the least amount of exogenous P.


Page 3

Other articles: Ringeval, B., B. Nowak, T. Nesme, M. Delmas, and S. Pellerin (2014), Contribution of anthropogenic phosphorus to agricultural soil fertility and food production, Global Biogeochem. Cycles, 28, 743– 756, doi:10.1002/2014GB004842. Tótha G., Guicharnauda R.A., Tóthb B., and Hermann T. (2014). Phosphorus levels in croplands of the European Union with implications for P fertilizer use. European Journal of Agronomy, Vol. 14, pp. 4252. http://www.sciencedirect.com/science/article/pii/S1161030113001950 Brunelle T., Dumas P., Souty F., Dorin B., Nadaud F. (2015). Evaluating the impact of rising fertilizer prices on crop yields. Agricultural Economics (to be published). Sustainable Phosphorus Management. A global transdisciplinary roadmap. Edited by Roland W. Scholz, Amit H. Roy, Fridolin S. Brand, Deborah T. Hellums, and Andrea E. Ulrich. Springer, 2014.

Nitrogen Article 6: In Food and feed trade as a driver in the global nitrogen cycle: 50-year trends, Luis Lassaletta and his colleagues analyze the increasing importance of the international trade of food and feed in the alteration of the N cycle at the global scale in two ways. First, using the information on food and feed trade across world countries, and assuming that N constitutes 16 % of proteins, they quantified the N annually traded in the period 1961–2010 and observed that in that period, the amount of N traded between countries has increased eightfold (from 3 to 24 TgN) and now concerns one third of the total N in world crop production, with the largest part corresponding to animal feed. Secondly, they divided the world into 12 regions and studied the N transfer among them in two reference years: 1986 and 2009. The N flow among these regions has dramatically intensified during this period not only due to an increase in the population but also in the proportion of animal protein in the diet of some countries. Nowadays, in terms of proteins and N, a small number of countries (e.g., USA, Argentina and Brazil) are feeding the rest of the world. At the global scale the system is becoming less efficient because of the disconnection between crop and livestock production across specialized regions, increasing the environmental impacts. As human diet is an additional clear driver of the observed changes, the solutions must rely not only on the producers, but also on the consumers. The

results of this study provide new insights into the food dependency relationships between the different regions of the world as well as the growing importance of international food and feed trade in the global N cycle. The map illustrates the changes in nitrogen fluxes from each region to the others for the year 1986 and 2009. Arrows show the fluxes between the regions (only fluxes higher than 90GgN are represented).


Page 4

Article 7: A tradeoff frontier for global nitrogen use and cereal production by N. Mueller and his colleagues shows that nitrogen fertilizer use across the world’s croplands enables high-yielding agricultural production, but does so at considerable environmental cost.

Other references J.-L. Peyraud, P. Cellier, C. Donnars, O. Réchauchère (coord.), F. Aarts, F. Béline, C. Bockstaller, M. Bourblanc, P. Cellier, L. Delaby, J.Y. Dourmad, P. Dupraz, P. Durand, P. Faverdin, J.L. Fiorelli, C. Gaigné, P. Kuikman, A. Langlais, P. Le Goffe, P. Lescoat, T. Morvan, C. Nicourt, V. Parnaudeau, J.L. Peyraud, P. Rochette, F. Vertes, P. Veysset , 2012. Les flux d’azote liés aux élevages, réduire les pertes, rétablir les équilibres. Synthèse du rapport d’expertise scientifique collective, INRA (France), 68 p.

Possible directions for agronomy Article 8: Global agronomy, a new field of research. A review, by David Makowski, Thomas Nesme, François Papy, and Thierry Doré, recommend that agronomists update their research objects, methods, and tools to address global issues. Yield trends and variations among various regions should be analyzed to understand the sources of these variations. Crop model simulations should be up scaled to estimate potential yields and to assess the effect of climate change and resource scarcity at the global scale. Advanced methods should analyze output uncertainty of complex models used at a global scale. Global datasets on the performance and environmental impact of cropping systems should be developed to allow agronomists to identify promising cropping systems. Crop yield increase rates are key parameters for foresight studies on food security, and their values are very variable both spatially (Fig. 2) and temporarily. The data from figure 4 data quantifying the effect of climate change on wheat yields were extracted from 90 published papers retrieved from the Web of Knowledge between 1991 and 2012.


Page 5

Article 9: Multiple cropping systems as drivers for providing multiple ecosystem services: from concepts to design (by Sabrina Gaba et al.) review examples of multiple cropping systems that aim to use biotic interactions to reduce chemical inputs and provide more ecosystem services than just provisioning. They conclude for a multidisciplinary approach combining genetics, ecology, and agricultural sciences, and market mechanisms and organization.

Article 10: Crop modelling for integrated assessment of risk to food production from climate change from F. Ewert et aL., show that studies on future climate risk to crop productivity must be able to approximate future management, as influenced by a range of socio-economic, biophysical and subjective factors, to varying degrees affected by climate change themselves.

Other reference: Sutton, M. et al. (2013). Our nutrient world: the challenge to produce more food and energy with less pollution. Technical report, Global Partnership on Nutrient Management and the International Nitrogen Initiative, Edinburgh. Global Overview of Nutrient Management. http://www.initrogen.org/sites/default/files/documents/files/ONW.pdf


Page 6