A comparison of soil liming requirement methodologies in temperate, Northern European pedo‐climates

Abstract

BackgroundLiming agricultural land is essential to optimise crop yield and soil nutrients. Despite the importance of pH management in agricultural soils, liming applications have been decreasing in the United Kingdom for decades. There is no comparison of contemporary and historical liming requirement (LR) methods for Northern European, temperate climate mineral soils high in organic matter (OM).AimsThe aims of this research were to thoroughly comparatively analyse current methodologies and to ascertain which soil characteristics contribute to LR reactions.MethodsAnalysis compared methods for determining liming values common in the United Kingdom (Scottish Agricultural College [SAC] look‐up chart, RothLime model), Europe and the United States (Shoemaker–McLean–Pratt, Sikora, Modified Mehlich buffers), and the 30‐min calcium hydroxide titration developed by the University of Georgia.ResultsRothLime and SAC highly underestimated the LR value in acidic soils. The buffers highly over or underestimated LRs. The UGA titration method is a cheap, easy and accurate method which could be utilised for high OM soils but requires further calculation development. The characteristics most associated with soil–lime reactions in this experiment were measures of exchangeability (cation exchange capacity and loss on ignition, and by proxy, lime buffering capacity).ConclusionsThere is an opportunity to create buffer calculators and titration equations adapted to high OM soils. These are suggested for further development, through a larger diversity of UK soil types grouped by buffering capacity ranges. Including soil exchangeability factors in lime management calculations may contribute to more accurate values and therefore better resource management. Increasing LR accuracy for site‐specific soil pH management, used in precision agriculture technologies, is a necessary tool for the conservation of natural resources like limestone, managing resource use efficiency, and for optimising yields.

Investigating the accuracy and comparability of various lime prediction methods for Irish grassland mineral soils

“…The Rothlime method was designed for simple on-farm calculations and thus uses rounded figures from broad variable inputs, for example, arable versus grassland, along with five types of soil from peats to sand. This ease-of-use approach (although it still requires the inputters to have a water-soil pH) thus will affect accuracy and it has been shown to overestimate the LR, particularly with more acidic soils (Boyko et al, 2023).…”