Soil Chemical Methods – Australasia describes over 200 laboratory and field chemical tests relevant to Australasia and beyond. The information and methodology provided across 20 chapters is comprehensive, systematic, uniquely coded, up-to-date and designed to promote chemical measurement quality. There is guidance on the choice and application of analytical methods from soil sampling through to the reporting of results. In many cases, optional analytical ‘finishes’ are provided, such as flow-injection analysis, electro-chemistry, multiple flame technologies, and alternatives to chemical testing offered by near-range and mid-range infrared diffuse reflectance spectroscopy. The book supersedes and updates the soil chemical testing section of the 1992 Australian Laboratory Handbook of Soil and Water Chemical Methods of Rayment and Higginson, while retaining method codes and other strengths of that Handbook. Chapters cover soil sampling, sample preparation and moisture content; electrical conductivity and redox potential; soil pH; chloride; carbon; nitrogen; phosphorus; sulphur; gypsum; micronutrients; extractable iron, aluminium and silicon; saturation extracts; ion-exchange properties; lime requirements; total miscellaneous elements; miscellaneous extractable elements; alkaline earth carbonates and acid sulfate soils. In addition, there are informative Appendices, including information on the accuracy and precision of selected methods. This book targets practising analysts, laboratory managers, students, academics, researchers, consultants and advisors involved in the analysis, use and management of soils for fertility assessments, land use surveys, environmental studies and for natural resource management.

This study was conducted to assess the usefulness of petiole sap nitrate and total nitrogen (N) in dried leaf for determining N status and yield response in capsicum (Capsicum annuum L.) grown with plastic mulch and trickle irrigation in subtropical Australia. Five rates of N (0, 70, 140,210, 280 kg/ha) were applied in factorial combination with 2 rates of potassium (K: 0, 200 kg/ha) in randomised block experiments to capsicum cv. Bell Tower grown at Bundaberg Research Station in spring 1990 and autumn 1991. Critical nutrient ranges for nitrate concentration in petiole sap and for total N concentration in dried youngest mature leaf blades plus petioles (YMB + P) were derived at different stages of crop development (bud development, BD; first anthesis, FA; 80% flowering, F; fruit set, FS). Sap nitrate was about 5 times more sensitive to changes in N application than total N. Petiole sap nitrate accounted for a greater amount of the variation in marketable fruit yield (quadratic square root relationships, 0.45 < R2 < 0.83) than total N concentration in dried YMB + P (linear relationships, 0.29 < R2 < 0.74). Simple linear regressions indicated a stronger relationship between applied N and petiole sap nitrate concentration than total N concentration in dried YMB + P (range in R2 values among 8 sampling events: 0.71-0.91 for petiole sap nitrate, 0.35-0.78 for YMB + P total N). For the fertiliser application strategy, 60% of N was applied pre-fruitset and 40% after. Sap nitrate concentrations associated with 95 and 100% of maximum marketable fruit yield increased from BD (5010-6000 mg/L spring, 4980-5280 mg/L autumn) to FA (6220-7065 mg/L spring, 555M000 mg/L autumn). After FA, the range progressively decreased to 1640-2800 and 520-1220 mg/L at FS, for spring and autumn, respectively. It was concluded that petiole sap nitrate was a better indicator of plant N status and yield response than total N concentration in dried YMB + P for capsicum in subtropical Australia. A critical petiole sap K concentration (corresponding with maximum yield and at which no yield response to K addition was measured) of >4800 mg/L was proposed by correlating sap K with yield responses.

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