ABSTRACT Different water management strategies should be investigated to ensure adequate water supply to furrow-irrigated soybean plants in lowlands. This study examined the performance and efficiency of furrow irrigation techniques and related them to the soybean yield potential in lowland fields of Southern Brazil in the 2017/18 growing season. An experiment was conducted on raised seedbeds to evaluate furrow irrigation techniques: full irrigation with cutback, irrigation during the advance phase with low inflow, irrigation during the advance phase (cutoff), surge irrigation, and no irrigation. The design parameters, efficiency of the techniques, agronomic characteristics, and the grain yield of the soybean crop, were evaluated. The overall performance of the cutback technique in furrow irrigation was superior, followed by the surge irrigation, cutoff, and low inflow techniques. Furrow irrigation increased soybean yield in lowlands, and the cutback technique was the best to guarantee the soybean yield potential in lowlands, resulting in a 29% yield increase compared to non-irrigated.

ABSTRACT Soil compression curve (CC) provides parameters to identify soil load-bearing capacity and susceptibility to compaction. An Excel add-in (ACC) incorporating graphical procedures for mathematical models for soil CC description and calculation of parameters was developed. By using the ACC, soil CC can be described by means of the Casagrande method, mathematically operationalized with the van Genuchten equation, with or without restrictions on its parameters, and by Dias Junior and Pierce method in its original form and also modified using the void ratio rather than soil bulk density. The ACC uses a single Excel spreadsheet for input and output data, in addition to a graphical interface and a tool for exporting editable charts. Compared to SAS statistical software, the ACC minimized the sum of squared residuals and estimated parameters of mathematical models with the same efficiency for 347 compression curves. The ACC programming script is available and can be modified or used as a framework for other programming projects.