STATEMENT TO THE AGRICULTURAL COMMUNITY
The Agrisus Foundation is using its website to release the Phosphorus Project Report, a unique survey in the history of Brazilian agriculture.
Soil samples were collected from the 0/5 and 5/10 cm layers at 1171 locations randomly selected in the main farming regions around the country. Sampling was carried out by Agroconsult teams in partnership with the Crop Rally Project 2009.
The analyses on the 2,342 samples and additional information has been collected in a database with over 63,000 entries compiled by ConPlant, in Campinas.
The Phosphorous report shows that there is a layer with a high P content available in most land used to grow soybeans and corn using no-till planting. This technology, which does not mix fertilizer in with the soil, provides a new edaphic environment for the nutrients provided to plants.
The results confirm the previous research supported by Agrisus, conducted in Rio Verde/GO, also explain the observations made by many farmers that certain areas where no-till planting is used show little reaction to phosphate fertilizing.
Data from the analyses indicate that most soils have been limed and that there are little difference in soybean yield between clay, loam or sandy soil. There are also small differences between soils with or without the high availability P layer, explained by the sufficient fertilizing of poorer land.
The results being released point towards the importance of additional observations and researching to determine in which situations P fertilizing can be limited to starting dosages, either 20/30 kg/ha of P2O5 along the furrow, thus cutting production costs.
The Agrisus Foundation believes that the P as well as K, Ca, Mg and other surveys based on the aforementioned database could help further refine the already advanced mineral nutrition technology for soybean and corn crops in Brazil.
THE PHOSPHORUS PROJECT
In February of 2009, we reported on approval of Project 541-09 which, alongside Project 534-09 “2009 Crop Rally”, aimed to take soil samples from layers where fertilizer is being applied year after year, without being incorporated into the soil, which occurs in the No-Till Planting System.
2342 samples were analyzed from 1171 random sites in the main cereal farming regions around the country, determining which elements had been extracted using the Agronomic Institute of Campinas-IAC ion exchange resin method, such as phosphorus, potassium, calcium and magnesium, as well as the pH, aluminum and hydrogen, based on which the sum of bases (SB), cation exchange capacity (CEC) and base saturation index (V%) were calculated.
Each sample was identified and the following on-site information was also recorded: depth, latitude, longitude, height, municipality, state, climate region, crop, productivity, soil coverage, soil moisture and texture.
This information was tabulated in a database with 2348 lines by 27 columns, containing over 63,000 pieces of data which have been carefully studied for the element phosphorus-P, the main thrust of this report.
We decided to limit this report to quantitative results so that specialists could contribute with explanations, considerations and conclusions based on their scientific and technical knowledge, as it is a well-known fact that plants quickly spread P throughout their living tissue when absorbed from any point in the soil where available.
The proven existence of a high level horizon of available Phosphorous at many of the points visited may lead to conclusions or serve as a basis for justify new experiments to confirm or amend current phosphate fertilizing recommendations.
Subsequent surveys may analyze the presence of the main bases, K, Ca and Mg, alongside other laboratory results from the database, expanding our knowledge in relation to the fertility of soils used to farm soybeans and corn under a No-Till System, confirming or improving current fertilizing methods.
The Agrisus Foundation believes this is the most important project it has financed in its eight years of activity. By providing access to the results from such as wide-ranging survey, the founders, Directors and technical collaborators at the foundation hope and believe they can offer a major data set whose interpretation could help improve national farming and livestock activities.
Fernando Penteado Cardoso-
President of Agrisus Foundation
SUMMARY OF RESULTS
1. The points sampled show a varied texture, predominantly clay soils in the southern climate region (page 4) of the country – this coincides with the longer period of No-Till System-NTS adoption – and sandy soils in more northern regions – coinciding with more recent NTS practices:
─Clay texture: R1 - 65%; R2 -64%; R3 -32%; R4 -23%;
--Sandy texture: R1 - 8%; R2 -11%; R3 -21%; R4 -35%;
2. The sampled points present various mulching proportions and different levels of Ca+Mg, according to the farming practices adopted, considering that in February the residues had undergone substantial decomposition:
--Coverage >40% (soybeans): R1 -71%; R2 -41%; R3 -28%; R4 -27%
--Ca+Mg changeable in mmlc/dm3
-- Layer at 0/5 cm: R1 -136; R2 -88; R3 -61; R4 -56
-Layer at 5/10 cm: R1 -106; R2 -77; R3 -46; R4 -45
3. The P levels extracted by resin exchange (IAC method and standards) indicate the presence of a high P horizon in part of the sampled layers when evaluated separately:
─ High P Horizon: 0/5 cm - 41%; 5/10 cm - 36%
4. The P content, extracted and evaluated using the IAC system, for both layers when looked at together confirm the existence of high P horizons at the sampled points:
─ High P Horizon: 0/5 or 5/10 cm 51%
5. Based on the fact that the 2 overlaid layers of “average” P mean the existence of a high P horizon that has been split, the climate regions in the soybean areas present variable proportions of points with high P horizons, most frequently in the South where NTS is more consolidated:
─ High P Horizon: R1 -89%; R2 -91%; R3 -75%; R4 -72%.
6. Based on the same criteria, clay soils present a higher proportion of points with high P horizons, which coincides with the more consolidated NTP regions where this type of soil predominates:
─ High P Horizon: clay-87%, loam-79%; sandy-70%
7. The residue mulch level does not provide a reliable correlation with the P level in any of the layers.
8. Soybean productivity does not present a correlation with soil texture or P content in any of the layers, while we should note that, in line with regional practices, plantations receive a 60/80 kg/ha application of P2O5 independent of the P content of the soil.
Full Report available at site "www.agrisus.org.br" (portuguese)