Automatic variable rate fertilisation system for improved fertilisation uniformity in paddy fields

Abstract

China currently relies on manual labour to fertilise paddy fields, hindering the improvement of fertilisation uniformity, management efficiency, and fertiliser use efficiency. Following a drastic decrease in the availability of agricultural labour, fertilisation operations are facing increasing labour costs and low reliability rates and this is threatening food security. This study developed an automatic fertilisation system suitable for pipe and canal irrigation systems in paddy fields, which measures the irrigation flowrate every second and adjusts the variation of the fertiliser flowrate to maintain a steady water-fertiliser ratio ( WFR ). An inexpensive single-chip microcomputer was used as the core of the system for precise control and tests were conducted to check its performance in concentration control. Results show that the fertilisation system developed in this study steadily controlled fertiliser concentration with a normalised mean absolute error ( NMAE ) ranging from 0.15% to 0.58% and from 0.22% to 0.63% for the tested pipe and canal irrigation systems, respectively. The fertiliser flowrate was adjusted to the irrigation flowrate instantly and accurately, with a maximum deviation of 0.56% in the WFR . This system drastically improved fertilisation uniformity compared to manual fertilisation, and had a Christiansen uniformity coefficient of 96.30%; a distribution uniformity of 0.93, and a coefficient of variation of 0.05. It also decreases labour costs, reduces potential pollutions and increases management efficiency. Thus, it can improve fertiliser use efficiency and contribute to the development of precision agriculture. • Automatic fertilisation system for paddy fields developed based on an SCM. • System is suitable for both pipe and canal irrigation systems. • Fertilisation is controlled by irrigation flowrate and responds to its change. • Fertiliser was applied with great precision and distributed uniformly in the field. • Proposed system can improve fertiliser use efficiency and reduce manual labour.