ABSTRACT
Many agronomists have a limited understanding of Brazilian farming systems. It may be possible to increase the agronomy efciency of these systems by adopting precision farming (PF) techniques. The purpose of this paper is to identify yieldlimiting factors (YLF) in Southern Brazilian farming systems, using PF as a tool to
3.1 Executive Summary ........................................................................................ 31 3.2 Introduction .................................................................................................... 32
3.2.1 Evolution of Soil Management in South Brazil .................................. 32 3.2.2 Adoption of Precision Farming in Southern Brazil ............................ 33
3.3 Methods and Main Equipments and Procedures Used ...................................34 3.4 Results ............................................................................................................. 38
3.4.1 Soil Variability in Southern Brazil Fields .......................................... 38 3.4.2 Variable-Rate Phosphorus, Potassium, and Lime Applications ......... 41
3.4.2.1 Yield Response to Variable-Rate Fertilizer .........................44 3.4.3 Temporal Variability in Soil Nutrients ...............................................44 3.4.4 Phosphorus and Potassium Apparent Soil Buffer Capacity
Determined by Nutrient Balance ........................................................ 45 3.4.5 Variable-Rate Nitrogen Fertilization in Real Time Using Optical
Spectroscopy .......................................................................................48 3.4.6 Yield Maps as a Tool to Improve Soil Management ........................... 51
3.5 Conclusions ..................................................................................................... 57 Acknowledgments .................................................................................................... 59 References ................................................................................................................ 59
improve soil and crop management. It is estimated that in Rio Grande do Sul State close to 1 Mha will be under PF by 2009/2010. Adoption of PF in this part of Brazil has increased exponentially over the past 7 years. Topics addressed in this chapter include (1) soil sampling for soil nutrients status evaluation; (2) soil nutrient variability in the eld; (3) spatial and temporal variability of soil nutrient concentration in PF; (4) soil buffering capacity; (5) variable rate lime, phosphorus, and potassium applications; (6) real-time N applications using optical spectroscopy; (7) use of yield maps as a tool to improve soil management; and (8) water availability impacts on temporal yield variability.
