Note: The following is an update on fertilizer practices in Argentina over the past 20 years. The changes in fertilizer practices over time in Argentina are impacting fertilizer demands in a global fertilizer economy.
Martin Navarro, Graduate Student, Plant and Soil Sciences
John Grove, Agronomic Soil Science, Plant and Soil Sciences
It will soon be spring in Argentina, and fertilizer purchase decisions are being made. Unlike the U.S., where fertilizer use has been a common practice for many years, Argentina’s linear growth in fertilizer use began only 20 years ago (Figure 1). This increased use of fertilizers has been associated with a continued increase in crop yield (Figure 2). It should be noted that the severe drop in fertilizer use in 2008 and 2009 was due to a reduction in the area of corn and wheat,with a corresponding increase in the area of soybean.
Figure 1: Fertilizer consumption in Argentina, from 1990 to 2009.
Figure 2: Annual grain (corn,
soybean and wheat, averaged together) yield in Argentina, from 1990 to 2009.
The nutrients most commonly purchased in Argentina are, in declining importance, nitrogen (N),phosphorus (P), sulfur (S), and potassium (K). Most soils found in the more productive region of Argentina (the Pampas) have high levels of bioavailable P because the soil parent material is rich in this nutrient. The use of S is increasingly common, as deficiencies of this nutrient are being increasingly detected. The soils of the Pampas are richer in bioavailable P, in comparison with
soils found in other agricultural regions in Argentina. However, Darwich (1999) has reported significant declines in bioavailable P in these soils, relative to original levels, relative even to levels existing in the early 1980’s.
Despite the large increase in fertilizer use in the past 20 years, nutrient replenishment (replacement of nutrients removed in grain) is still very low and a topic of long-term concern.The fraction of total nutrient uptake that is recycled back to the soil averages about 34%, and replenishment of nutrient stocks with fertilizer averages about 41% for N, 61% for P, 6% for K,and 35% for S. This suggests that these soils will be progressively poorer in their fertility. This problem was also evaluated by Ciampitti and Garcia (2008), for soils of the Pampas region, and they concluded that only 31, 53, 1 and 27 % of the N, P, K and S, respectively, exported by crop harvest was replaced by fertilizer addition.
The situation has been improving with time, though only slightly (Figure 3). Phosphorus and sulfur replacement have made slow but steady progress, in part because fertilizers containing these nutrients are now being more routinely applied to soybean, the crop with the largest production area in Argentina. The Argentine fertilizer industry, as well as various Argentine governmental institutions, expects increased fertilizer consumption and greater nutrient replenishment, especially for nitrogen. This expectation is based on anticipated increases in the
production areas of both wheat and maize. In Argentina, these cereal crops are generally better fertilized than soybean. Current wheat and maize production areas are now at their lowest levels in 30 years.
In conclusion, Argentine nutrient management is generally characterized by a negative soil nutrient balance, due to rates of replacement/fertilization that are lower than rates of removal. This has resulted in declines in bioavailable N, P, K, and S levels in Argentine soils. Given this context, appropriate fertilizer rates and sources are important to crop production in Argentina, slowing/preventing nutrient export and depletion of soil fertility. Diagnosis of the fertility needs for a field is based in knowledge of the field’s soil and soil testing is important to that knowledge base. Soil chemical analysis and good nutrient management practices are tools indispensable to sustainable Argentine agriculture.
Figure 3: Nutrient
application/removal ratios in Argentina from 1993 to 2007.
Darwich N. 1999. Niveles de P disponible en suelos pampeanos. (Levels of bioavailable P in soils of the Pampas). IDIA 409-412: 1-5. INTA. Buenos Aires, Argentina.
Ciampitti I., F. Garcia. 2008. Fosforo en rotaciones agrícolas de la región pampeana central: II. Balance de P. (Phosphorus in agricultural rotations in the central Pampas region: II. P balance). Actas CD XXI Congreso Argentino de la Ciencia del Suelo. AACS. Potrero de los Funes, San Luis.