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Potassium fertilisation strategies for rotational grain-legume crops — Implications for the subsequent sugarcane crop

Halpin, N. V., Bell, M. J., Rehbein, W. E. and Moody, P. W. (2019) Potassium fertilisation strategies for rotational grain-legume crops — Implications for the subsequent sugarcane crop. In: 41st Australian Society of Sugar Cane Technologists Conference, ASSCT 2019, University of Southern Queensland (USQ)Toowoomba; Australia.

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Abstract

Sugarcane is regarded as a luxury accumulator of potassium (K). Soil testing at plough-out of older ratoons prior to establishing grain-legume crops (soybean and peanuts) sometimes highlights low soil reserves of the element. Agronomists have been seeking guidance on fertilization strategies to maximize break-crop grain yields in sugarcane soils that have depleted K levels. A replicated field trial was established to determine the effect of a range of K fertilizer additions on the productivity of a soybean and then a peanut crop in a long fallow from sugarcane. The residual value of the K supplied in the legume phase was also assessed in the subsequent sugarcane crop. Despite the additions of K from 0 to 250 kg K/ha in 50 kg increments there was no productivity response in either legume crop. The subsequent plant-cane crop (Q208A) also demonstrated no productivity response to K fertilizer that was applied to the soil prior to the establishment of the soybean crop. Analysis of plant-cane K concentrations showed no difference in K returned to the site as trash. However, there were significant differences in the quantities of K exported off-farm in millable stalk. The lack of fertilizer K responses, despite low soil-test K concentrations at the end of the sugarcane crop cycle, suggest considerable uncertainty in the interpretation of current soil-testing strategies remains. However, it is unsustainable to mine soil nutrients. Growers have two options; either to supply enough K to meet expected legume crop removal or alternatively recognize that if K is over-supplied to the legume phase, then there is the opportunity to ‘discount’ that in the plant-cane fertilization strategy. © 2019 Australian Society of Sugar Cane Technologists. All rights reserved.

Item Type:Conference or Workshop Item (Paper)
Business groups:Crop and Food Science
Keywords:Farming systems Grain legume rotations Potassium Engineers Fertilizers Productivity Soil testing Soils Sugar cane Crop grain yields Farming system Fertilisation Field trial Grain legume Residual value Sugarcane crops Testing strategies Crops
Subjects:Agriculture > Agriculture (General) > Soils. Soil science > Soil and crops. Soil-plant relationships. Soil productivity
Agriculture > Agriculture (General) > Methods and systems of culture. Cropping systems
Agriculture > Agriculture (General) > Fertilisers
Plant culture > Field crops > Grain. Cereals
Deposited On:28 Apr 2020 02:29
Last Modified:28 Apr 2020 02:29

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