Nutritional evaluation of nitrogen and potassium fertilization of carob tree under dry-farming conditions

• Published in: Communications in soil science and plant analysis 2008-02, Vol.39 (5-6), p.652-666
• Main Authors: Correia, P.J, Pestana, M, Domingos, I, Martins-Loucao, M.A
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; application rate; Biological and medical sciences; Ceratonia siliqua; chemical constituents of plants; dry environmental conditions; dryland farming; fertilizer application; Fruits; fruits (plant anatomy); Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; leaves; linear models; nitrogen; Nitrogen, phosphorus, potassium fertilizations; nutrient uptake; nutrients; plant nutrition; potassium; seasonal variation; shrubs; Soil-plant relationships. Soil fertility. Fertilization. Amendments; SPAD; trees; yield; yields
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1080/00103620701879075

The aim of this work was to assess how potassium (K) and nitrogen (N) fertilization might affect the variation of leaf and fruit nutrient concentrations in carob tree (Ceratonia siliqua L.) under low precipitation. A field study was conducted in 1997, 1998, and 1999 in a calcareous soil. Four fertilization treatments were tested: no fertilizer (C), 0.8 kg N tree −1 (N treatment), 0.83 kg K tree −1 (K treatment), and 0.80 kg N tree −1 plus 0.83 kg K tree −1 (NK treatment). During the hydrological cycle 1998/1999, only 250 mm of rain were recorded. Because of this, from 1998 to 1999 a decrease in the concentrations of mobile nutrients N, phosphorus (P), and K and an increase in calcium (Ca), iron (Fe), and manganese (Mn) were observed in leaves. The application of N led to higher leaf N concentration compared with other treatments. This response allowed the establishment of a linear model that relates soil plant analysis development (SPAD) readings with leaf N concentrations (r 2 =0.55; P