Comparing tools for determining crop nutrient requirements

By carefully balancing the use of nitrogen, phosphorus and potassium fertilisers with crop demands, a nutrient management plan (NMP) aims to enhance crop production while reducing environmental harm due to over fertilisation. As several tools with different complexities can assist farmers in their fertiliser decisions, the characteristics of 14 of the most widely used NMP tools across Europe, China, and New Zealand were compared. All NMP tools considered the field spatial scale, seasonal time scale, and utilised a mass balance approach. To evaluate the tools, matrices of presence/absence of 24 characteristics for their practical use, 22 nutrient cycle processes and 38 required input data were compiled, and cumulative scores were calculated. In addition, two case studies were performed to compare the outputs of NMP tools. Decision support systems such as grano.net®  and TUdi tool were highly adaptable and comprehensively described nutrient processes while considering many inputs. By considering only the most important nutrient processes and requiring fewer inputs, software such as PLANET_MANNER and spreadsheets such as Fert_Office were moderately adaptable. Conversely, reference tables tools such as MEM-NAK and Bulgarian tool considered only essential nutrient processes and few inputs and demonstrated limited adaptability. Fertiliser recommendations varied considerably, mainly due to differences in calculating crop nutrient uptake. For a broader application of the NMP tools, differences in the algorithms used to estimate each process, in soil and climate conditions, and in national regulations must be considered. Furthermore, interoperability should be improved in next-generation NMPs to enable data exchange between platforms