Nitrogen and micronutrients have a key role in many citrus plant enzyme reactions. Although enough micronutrients may be present in the soil, deficiency can develop due to soil depletion or the formation of insoluble compounds. The objectives of this study were to (1) determine the adsorption, distribution, and availability of Zn in a sandy soil; (2) compare the effectiveness of foliar and soil application methods of Zn on Huanglongbing [HLB] affected trees; (3) compare foliar application rates of Zn for HLB-affected trees; (4) determine the effect of N rates on yield, soil inorganic N distribution patterns, and tree growth parameters. Tree rows were supplied with three N rates of 168, 224 and 280 kg·N·ha−1 and Zn at single and double recommended rates (recommended rate = 5.6 kg·Zn·ha−1) using foliar and soil application methods, in a split-plot experimental design. The results show that Zn concentration in the 0–15 cm soil depth was three times higher than the 30–45 and 45–60 cm soil depths during the study. An adsorption study revealed high Zn (KD = 6.5) sorption coefficients at 0–15 cm soil depth, while 30–45 and 45–60 cm depths showed little sorption. Leaf Zn concentration for foliar spray was two times higher than the soil application method. A nitrogen level of 224 kg N ha−1 improved canopy volume when compared to other N levels at the expense of reduced fruit weight. Foliar Zn application at 5.6 or 11.2 kg ha−1 and N rate at 224 kg ha−1 appear to be adequate for improving the performance of HLB-affected citrus trees.

Solute fate in soil-plant continuum could either be soil or leaf uptake or leaching beyond the rooting zone. An adsorption coefficient (KD) is an important chemical property to describe the interaction between the solute and soil, affecting the solute movement in soils from one point to another. Boron (B), manganese (Mn), and zinc (Zn) uptake are evident in the leaves as a constituent of photosynthesis and other plant body-building mechanisms for growth and development. This study investigates the availability of micronutrients (B, Mn, and Zn) to citrus trees through modified application methods and rates. Leaf samples were collected from experimental plots arranged in a randomized complete block design, with 4 micronutrient treatments: control, foliar ×1, foliar ×2, and soil ×1. Boron, Mn, and Zn rates were 1.12, 10.08, and 5.60 kg ha−1, respectively. Composite soil samples were randomly collected at 5 points, and a 1-point adsorption study was conducted in 4 soil depths at an increment of 15 cm from the soil surface. Adsorption coefficient (KD) for Mn and B was 22 and 3 times higher at 0–15 cm than at soil depth of 15–60 cm. The adsorption coefficient (KD) for Zn was 2.5 times greater at 0–15 cm than 15–30 cm soil depth, while there was little or no sorption at 30–60 cm. Leaf Mn and Zn concentrations showed that foliar spray was 2 times higher than the soil application method, while B showed that the soil application method was 2 times higher than foliar application method for 2 seasons sampling events. Thus, the behavior of B, Mn, and Zn in the soil via adsorption coefficient (KD) reflects the availability of B, Mn, and Zn in the citrus leaves.

ÖZETu çalışma farklı dozlarda uygulanan olgunlaştırılmış çiftlik gübresinin lahana, kereviz ve pırasada verim ve bazı kalite özellikleri üzerine etkisini belirlemek amacıyla yürütülmüştür. Araştırmada sebze yetiştiriciliğinde yaygın olarak tercih edilen kontrol, 2, 4, 6 t da -1 dozlarında olmak üzere üretim alanlarına çiftlik gübresi uygulanmış ve çalışma 2013 ve 2014 üretim döneminde açık tarla koşullarında yürütülmüştür. Elde edilen sonuçlar iki deneme yılında da çiftlik gübresi uygulamalarının incelenen kalite özellikleri (renk parametreleri hariç) ve verim üzerine pozitif etkide bulunduğunu ortaya koymaktadır. Çiftlik gübresi uygulama dozunun artması ile incelenen bitki kalite parametrelerinin de arttığı gözlenen çalışmada, iki deneme yılında da en yüksek verim 4 ve 6 t da -1 dozlarında çiftlik gübresi uygulanan alanlardan elde edilmiştir. ABSTRACThe main objective of this research was to determine the effects of different level of farmyard manure application on yield and quality parameters of cabbage, leek and celeriac. In the experiment five treatments namely; control (no manure) and the common recommended rates (2, 4, 6 t da -1 ) were applied during the 2013 and 2014 growing period under the field conditions. The results revealed that application of farmyard manure positively influenced plant quality traits (except colour properties), and yield of celeriac, cabbage and leek compared with control plots in both years. An increased in the application rates promoted plant quality traits and the highest yields in the three species were obtained from at the rate of 4 and 6 t da -1 farmyard manure applications.