Abstract
The impact of polymer-based slow-release urea formulations on soil microbial N dynamics in potatoes has been sparingly deciphered. The present study investigated the effect of a biodegradable nano-polymer urea formulation on soil enzymatic activities and microflora involved in the N cycling of potato (Solanum tuberosum L.). The nano-chitosan-urea composite (NCUC) treatment significantly increased the soil dehydrogenase activity, organic carbon content and available potassium compared to the conventional urea (CU) treatment. The soil ammonical nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) contents and urease activity were significantly decreased in the NCUC-amended soil. The slow urea hydrolysis rate led to low concentrations of NH4+-N and NO3−-N in the tested potato soil. Furthermore, these results corroborate the low count of ammonia oxidizer and nitrate reducer populations. Quantitative PCR (q-PCR) studies revealed that the relative abundance of eubacterial (AOB) and archaeal ammonia-oxidizing (AOA) populations was reduced in the NCUC-treated soil compared to CU. The abundance of AOA was particularly lower than AOB, probably due to the more neutral and alkaline conditions of the tested soil. Our results suggest that the biodegradable polymer urea composite had a significant effect on the microbiota associated with soil N dynamics. Therefore, the developed NCUC could be used as a slow N-release fertilizer for enhanced growth and crop yields of potato.
Highlights
Potato (Solanum tuberosum L.) is one of the most abundant and widely cultivated vegetable crops in the world
After incorporation of urea (10% w/v) into chitosan (1.5% w/v), dichotomization of the absorption peak at 220 nm occurred with the appearance of a blue-shifted shoulder peak at 200 nm
Scanning Electron Microscopy (SEM) images further corroborated the Transmission Electron Microscopy (TEM) results, indicating that the higher concentration of urea (10% w/v) in chitosan resulted in a decrease in the pore size of the nano-chitosan-urea composite (NCUC) matrix (Figure 1B), which may be due to the enhanced networking followed by the formation of rodlets and rodlet bundles within the matrix
Summary
Potato (Solanum tuberosum L.) is one of the most abundant and widely cultivated vegetable crops in the world. The input of N fertilizers has been increased over the years to maximize tuber yields; excessive application of N fertilizers may reduce tuber yields [4] It significantly influences N cycling and augments NH3 + emissions (volatilization) and NO3 − -N accumulation (leaching), which have serious environmental implications [5]. This calls for the development of effective N management strategies such as controlled-release fertilizers (CRF) to improve N use efficiency and to combat the environmental impact of fertilizer application [6]
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