Effects of Different Organic and Inorganic Fertilizers on Growth and Yield of Cucumis anguria L.

Vegetables supply energy, vitamins, minerals, and other protective compounds needed for a balanced diet, and their importance is increasing globally as food systems respond to rising concerns about nutritional security [1]. Among vegetable crops, gherkin (Cucumis anguria L.), a member of the family Cucurbitaceae, is valued both as a food crop and as a commercially important export vegetable, known by several common names including bur cucumber, bur gherkin, cackrey, and gooseberry gourd. In some contexts, the term "gherkin" also refers to a pickled cucumber product derived from a different cultivar group of Cucumis sativus L. [2]. Gherkin has also been associated with traditional medicinal uses such as treating kidney stones, hemorrhoids, stomach pain, and jaundice [3].

In Sri Lanka, gherkin is a commercially important vegetable crop cultivated mainly for export in processed and semi-processed forms, with major destinations including China, Australia, Taiwan, Malaysia, Japan, and the Netherlands [4], [5]. Pickling-style gherkins have been produced for the export market since 1988, with cultivation extending from the dry zone to the intermediate zone [6]. Rising global demand for sustainably produced vegetables has increased interest in organic production systems, though organic gherkin production in Sri Lanka remains insufficient to meet market demand [5]. Expanding production while maintaining soil health is therefore a priority, since improving soil nutrient availability and retention supports stronger plant growth and higher yields [7].

Soil fertility is a major factor determining the productivity of short-duration crops such as gherkin. In the dry zone of Sri Lanka, declining soil fertility, low organic matter content, and limited nutrient retention can reduce crop performance if nutrients are not supplied properly, particularly in sandy regosols common to the Batticaloa district [8]. Nutrient deficiency can also increase susceptibility to plant disease, reducing yields and raising production costs for farmers [9]. Since gherkin has a relatively short growth cycle of around 60 days, it requires timely and balanced nutrient management to achieve good vegetative growth and fruit production [10]. Despite high market demand, average gherkin yields in Sri Lanka remain poor compared with major producing countries, indicating a need for improved agronomic practices [11].

Organic amendments such as cow dung, poultry manure, compost, and crop residues are widely recognized for improving crop productivity and soil quality, while also enhancing the physical, chemical, and biological properties of soil [12]. Organic manures increase soil organic carbon and nitrogen levels and promote water-stable aggregate formation compared with chemical fertilizers alone [13], [14]. Cattle dung contains macronutrients (N, P, K) along with secondary and micronutrients including calcium, magnesium, sulfur, zinc, boron, and copper [15], [16]. Poultry manure is often considered the most nutrient-dense animal manure, typically containing 0.9-1.5% nitrogen, 0.4-0.5% phosphorus, and about 0.8% potassium [17]. Compost serves as a slow-release nutrient source, supplying potassium, sulfur, calcium, and magnesium in addition to nitrogen and phosphorus [18].

Inorganic fertilizers remain important because they provide nutrients in readily available forms and can correct deficiencies quickly [19]. However, their continuous and exclusive use has been linked to soil degradation, nutrient imbalance, acidification, and declining soil biological activity under intensive cultivation [20]–[22], while prolonged nitrogen use can also increase pest pressure [23], [24]. These concerns make incorporating organic manure into farm practice increasingly important [25].

Combining organic and inorganic fertilizers offers advantages neither source provides alone: organic manures improve soil structure, water retention, aeration, and microbial activity, while inorganic fertilizers supply nutrients quickly to meet immediate crop demand. Used together, they improve nutrient availability in the root zone, support more efficient crop growth [26], [14], reduce dependence on costly chemical fertilizers, and improve long-term soil productivity [27], [28].

Although several studies have shown the benefits of organic manures and integrated fertilizer use in vegetable production, including recent trials on Cucumis anguria L. under Sri Lankan conditions using alternative organic and bio-enriched fertilizers [29], [8], information on the most suitable combination for Cucumis anguria L. cv. Chandani under dry-zone conditions in Sri Lanka remains limited. The response of gherkin to different proportions of poultry manure, cattle manure, compost, and inorganic fertilizer under local soil and climate conditions has not been sufficiently documented, and fertilizer recommendations developed for other crops or environments may not be directly applicable to gherkin production in the dry zone. The present study was therefore conducted to evaluate the effects of different combinations of organic and inorganic fertilizers on the growth and yield of Cucumis anguria L. cv. Chandani, and to identify the most effective treatment for sustainable and profitable production under dry-zone conditions in Sri Lanka.