Effect of Placement and Amount of Applied Phosphatic Fertilizer on the Early Growth of Direct-sown Onions (<i>Allium cepa</i> L.) on Andosols

Abstract

We investigated the influence of the placement and amount of the applied calcium superphosphate on the early growth of direct-sown onions (Allium cepa L.) on Andosols. The effect of localized fertilizer application was compared with broadcast application. The placement of calcium superphosphate below the onion seed may affect the early growth of onions, especially in the early growth stage. Fertilizer placed 0 to 4 cm below the seed was more effective than broadcast application. Seedling emergence based on the amount of calcium superphosphate 0 cm below the seed was not affected by the amount of calcium superphosphate in our experiment. The soil solution EC value of localized calcium superphosphate did not affect seedling emergence. These results suggest that the most effective placement of phosphatic fertilizer is directly below the seeds, and the effective amount to be applied is 30 or 45 kg・10 a

Evaluation of the Relationship Between Growth Parameters for Spring-sown Onion Cultivation in Tohoku, Japan

“…Therefore, finding an index for onion growth that can be evaluated by each farmer at the field level will contribute to the stable production of onions in emerging production areas. Previous studies on onion production have been conducted under various conditions, such as fertilizer application (Usuki et al 2015;Suesada et al 2018;Usuki & Muro 2018;Usuki et al 2019;Kudo et al 2020Kudo et al , 2021, irrigation (Nakano & Okada 2012, Abdelkhalik et al 2019, cropping type (Kinoshita et al 2018;Ikeda et al 2019Ikeda et al , 2020, and alternate cultivation methods (Brewster 2008;Katayama & Yamasaki 2014, 2015. Usuki et al (2019) reported that the number of expanded leaves can be accurately estimated from the accumulated daily air temperature data, suggesting that the onion growth stage can be estimated from the air temperature.…”