Status of nitrogen, phosphorus and potassium nutrient elements in rice fields in Rejosos District, Nganjuk Regency

¹ PSDKU Manajemen Agribisnis Kab Nganjuk, Jurusan Manajemen Agribisnis, Politeknik Negeri Jember, Jl. Mastrip 164, Jember, East Java, Indonesia
² PSDKU Manajemen Agribisnis Kab Bondowoso, Jurusan Manajemen Agribisnis, Politeknik Negeri Jember, Jl. Mastrip 164, Jember, East Java, Indonesia
³ PSDKU Manajemen Agroindustri Kab Sidoarjo, Jurusan Manajemen Agribisnis, Politeknik Negeri Jember, Jl. Mastrip 164, Jember, East Java, Indonesia

Abstract

Shallots (Allium ascalonicum L.) are a key horticultural commodity in Nganjuk Regency, where continuous monocropping poses a risk of nutrient depletion and soil degradation. However, information on macronutrient dynamics under different rotation practices remains limited. This study aims to quantify the soil macronutrient status (N, P, K) in shallot fields with and without rotation in Rejoso District and identify the major limiting nutrient for fertilizer management. A total of 16 composite soil samples were collected purposively from six villages representing contrasting cropping patterns. Samples were taken at 0–20 cm depth prior to harvest and analyzed using the Paddy Soil Test Kit (PUTS). Nitrogen levels were predominantly moderate (56%), followed by high (31%) and very high (13%). Phosphorus remained high across all locations, while potassium was mostly low (56%). Slightly acidic pH (5.6–6.0) corresponded with high P availability, whereas persistent K deficiency indicated nutrient mining under intensive cultivation. These findings emphasize potassium as the key limiting factor and highlight the need for balanced, site-specific fertilization through liming, organic amendments, and implementation of the 5R fertilization principle. Integration of yield response trials is recommended to support sustainable soil fertility improvement in shallot production systems..