Zeolite and urea = more nitrogen in the soil + increased yield
Zeolite and urea = more nitrogen in the soil + increased yield: this is the experimental result of an interesting study by three scientists from Malaysia.
The study was carried out at Universiti Putra by Omar Latifah, Osumanu Haruna Ahmeda and Nik Muhamad Abdul Majid in collaboration with the Malaysian Ministry of Higher Education.
The experiment
The high cost of nitrogen fertilisers leads to practices aimed at optimising their use, whilst minimising nitrate losses. Ammonium adsorption inhibits the loss of nitrogen in the form of nitrate, thereby increasing the availability of nitrogen to crops. Due to the negatively charged nature of nitrates, they move freely in the soil solution and are not adsorbed onto the surfaces of soil particles. Therefore, in this study, zeolite – specifically clinoptilolite – was used to adsorb and desorb ammonium. This enabled the determination of:
- the total nitrogen availability in the soil, the exchangeable ammonium and the available nitrates, and
- the ability of zeolite to adsorb ammonium from different concentrations of urea.
This study therefore investigated nitrate leaching and the availability of nitrogen in the soil following the application of zeolite and urea. The crop used in the experiment was maize (Zea mays L). The experiment was carried out using five different combinations with the following ratios:
- soil
- soil and urea (13 kg/stremma)
- soil, urea (13 kg/stremma) and zeolite
- soil, urea (9.75 kg/stremma) and zeolite
- soil, urea (6.5 kg/stremma) and zeolite
The conclusion
In all cases where zeolite was added, it appears that the release of ammonium and nitrate from the urea was significantly reduced. zeolite increased the retention of total soil nitrogen and exchangeable ammonium. It also increased the proportion of available nitrates, due to its high cation exchange capacity. It thus improved nitrogen availability through temporary retention at its exchange sites.
As a general conclusion, the addition of zeolite to urea in agriculture may constitute a potentially effective approach to improving the availability of nitrogen in the soil and, by extension, increasing the productivity of crops.
Download the study here