Exploring Potassium Deficiencies in the Northern Pampas of Argentina

Brief background to the problem:
In Argentina, the area cropped to soybean increased from 9 to 18 million ha and the production from 20 to 52 million t in the last 10 years. Despite of the large adoption of no-tillage, this increase in cropping area resulted in the degradation of soil fertility because of reduced crop rotations and negative nutrient balances. In the Pampas, the yield gap between well managed fields, under rotation and following the 4Rs nutrient concept, and other fields is of 2, 4, and 1.5 t/ha for wheat, maize, and soybean, respectively.
Intensification of agricultural systems without correct fertilization in the central and northern areas of Santa Fe province resulted in the constant reduction of soil nutrient reserves, staring by nitrogen, then phosphorus, and later sulphur and calcium. Under these conditions, it is expected that nutrients such as potassium (K) and magnesium become deficient in the near future.

P and K market development hypothesis (potential impact, reason for involvement, etc):
This research will explore potential areas of K deficiency in central and northern Santa Fe province as well as evaluate potential responses in grain crops and alfalfa. The area under grain crops and alfalfa in this region is of 1,500,000 ha.

Brief work plan (time line, resources, etc.):
The objectives of this research are: 1. To evaluate soil K availability at central and northern Santa Fe, and 2. To study K responses in soybean, wheat, and maize crops, and alfalfa.
Field experiments will be established in the central and northern regions of Santa Fe for grain crops (soybean, wheat, maize) and alfalfa at Reconquista, Gobernador Crespo, San Justo, Emilia, Esperanza, and Humboldt (six sites per cropping season).
Research will be conducted along three cropping seasons: 2011 through 2014.
The experiments will be conducted by staff of EEA INTA Rafaela and collaborators from local coops in commercial farms.
Experiments will be established in fields with long cropping history under no-tillage in a randomized complete block design with four replications, evaluating the following treatments:

1- Check
2- 50 kg KCl
3- 100 kg KCl
4- 200 kg KCl

N, P, S, and Ca will be applied to all treatments to avoid other nutrient limitations.
Soil testing at planting will include: nitrate-N, Bray P, organic matter, pH, exchangeable cations (Ca, Mg, K, Na), and CEC.
Grain yield and grain K concentration and removal will be determined at harvest.

Expected outputs (publications, meetings, workshop, etc.):
· Results of this work will be presented at different professional and farmer’s meetings organized by EEA INTA Rafaela, local coops, and other organizations.
· Partial reports will be prepared for farmers and agronomists in the area and published in local media.
· A final report will be available to prepare articles for Better Crops and Informaciones Agronómicas.