Juan Sánchez-Andreu

HUMIC SUBSTANCES AND AMINO ACIDS IMPROVE EFFECTIVENESS OF CHELATE FeEDDHA IN LEMON TREES

ABSTRACT Lemon trees cv. Fino were fertilized with mixtures of FeEDDHA and humic compounds (leonardite) or aminoacids. All the treatments improved the iron (Fe) uptake respect to a control fertilized only with FeEDDHA. The effect was more marked with humic substances (HS). The copper (Cu) uptake also increased, which can be a direct effect of the organic compounds, or indirect as a consequence of the release of EDDHA after Fe uptake. Humic compound also improved fruit weight. Vitamin C was affected by all the treatments depending on the ripening condition of the lemons (in a cold chamber or in the field).

Improvement of Iron Uptake in Table Grape by Addition of Humic Substances

ABSTRACT Two experiments in consecutive years were conducted at a table grape plantation located in southeastern Spain. The objective was to test whether the addition of commercial organic compounds could improve the uptake of iron (Fe) by plants. A commercial humic substance and two mixtures of amino acids were used as organic compounds in the first experiment and FeEDDHA was the source of Fe. The joint addition of FeEDDHA and organic compounds improved Fe nutrition. The humic substance was more effective than the amino acids in increasing Fe uptake. In the following year, a similar experiment was conducted by progressively replacing part of the chelate with the humic substance. An increase in foliar Fe and phosphorus (P) and a decrease in sodium (Na) levels were observed. The best results with respect to nutrient foliar content and nutrient relationships were obtained for a range of substitutions for the chelate by the humic substance of from 30% to 50% with no loss in yield or fruit quality.

Use of Humic Substances and Amino Acids to Enhance Iron Availability for Tomato Plants from Applications of the Chelate FeEDDHA

ABSTRACT Two experiments in consecutive years were conducted in a commercial greenhouse located in the Southeast of Spain. The objective was to test if the addition of commercial organic compounds could improve the uptake of iron (Fe) by tomato plants (Lycopersicon esculentum mill.) cv Daniela. A commercial humic substance (HS) and a mix of amino acids (AA) were used as organic compounds in the first year of the experiment, and FeEDDHA (Q) as a source of iron. Both organic compounds improved iron uptake in comparison to a control without the addition of organic materials, especially the humic substance. A similar experiment was conducted the following year, but part of the chelate was progressively substituted by the humic compound. Results showed that the content of iron in the leaves increased with the substitution without any significant losses of yield or fruit quality. Plant nutrition was also improved because of an increase in the level of phosphorus in the leaves and a decrease in foliar sodium levels indicating a reduction in the effects of salinity.

Effect of humic amendments on inorganic N, dehydrogenase and alkaline phosphatase activities of a Mediterranean soil

Dehydrogenase activity, alkaline phosphatase activity and NH4+, NO2− and NO3− concentrations were monitored in an aridisol treated with three commercially available humic amendments. The materials were of plant residue, lignite and peat origins. The humus plant residues, fulvic acids, with a high content of Kjeldahl-N, sustained high enzyme activities and highest levels of NH4+, NO2− and NO3−. Humus lignite (mainly humic acids) produced the highest dehydrogenase activity, whereas the alkaline phosphatase activity was not as high as that amendment with humus plant residues. The lower activity of alkaline phosphatase could not be attributed to the higher P content of humus lignite. Nitrification was also low, probably due to the low N content of this fertilizer. The amendment of humus peat origin (only humic acids) did not increase enzyme activity or inorganic N concentrations of soil. Our results show that although these materials are widely utilized and recommended as microbial and plant activators, they all behave very differently, and the effects on soil microbiological activity cannot be predicted solely on the basis of their humic and/or fulvic acid contents.

Influence of organic compounds on nitrogen‐fertilizer solubilization

Abstract In the attempt to find new products which release nutrients in gradual forms, the behavior of two commercial fertilizers was studied, Nitrophoska® (N) and urea (U), covered with two organic materials, humic acid (HA) and alginic acid (AA). The release of nitrogen from the fertilizers was determined by electroultrafiltration (EUF). These applied materials on the fertilizer surface resulted in a slowing of the release of nitrogen, although strictly speaking, these compounds do not function as coated fertilizers. Their effectiveness depends on the fertilizer, for with Nitrophoska®, the addition of alginic acid was more effective, while for urea, the addition of humic acid slowed the release of nitrogen.

Role of eddha and humic acids on the solubility of soil phosphorus

Abstract A greenhouse pot experiment was designed in order to test the effect that the addition of two organic materials, EDDHA and humic acid would have on the availability of P released from three P fertilizers, 8–24–8, 20–20–20, and MAP (monoamonium phosphate). Phosphorus was extracted from soil by three different methods (Burriel‐Hernando, Olsen, and EUF). Burriel‐P and EUF‐P were correlated according to the equation: Burriel·P = 3.9 × Fraction I + 2.7 × Fraction II + 23.5: r = 0.7558 where: Fraction I = EUF‐P, 200 V, 30 min; and Fraction II = EUF‐P, 200 V, 5 min. This relationship indicates that the Burriel‐Hernando method extracts both, soluble and insoluble forms of P. The effect of the organic additions depend basically on the kind of fertilizer employed. EDDHA increased P availability from 8–24–8, and humic acid did the same for MAP. The differences between treatments for 20–20–20 were also dependent on the method of P extraction.

EFFECT OF COPPER, NICKEL, ZINC, AND PHOSPHORUS ON REACTIONS OF FeEDDHA AND FeEDDHMA ISOMERS UNDER VARIABLE pH

The complexes of iron and o-EDDHA or EDDHMA decompose at low pH values although they are quickly recovered when pH increases. However this later reaction is affected by the occurrence in solution of cations different from iron or anions different from the chelating ligand. The influence of these ions depends on the chelate and on the isomeric form. In general, the isomer with lowest stability constant is the most affected. Copper and phosphate are the ions that impede to the greatest degree the recovery of FeEDDHA and FeEDDHMA. This study demonstrates that FeEDDHA is more stable than FeEDDHMA with respect to Cu2+, however, in regard to phosphate, FeEDDHMA shows higher percentages of recovery.

Kinetics of reactions of chelates FeEDDHA and FeEDDHMA as affected by pH and competing ions

Abstract Iron chelates are widely used in fertigation because of their high stability and solubility. However, sudden changes of pH or concentrations of accompanying ions affect chelate stability and make kinetics as relevant as equilibrium data. The kinetics of FeEDDHA and FeEDDHMA reactions at acidic pH values in the presence and absence of calcium (Ca), magnesium (Mg), phosphorus (P), copper (Cu), nickel (Ni), and zinc (Zn) were studied. The FeEDDHA and FeEDDHMA decompound in few seconds at low pH values. The extension of the decomposition reaction is affected by the kind of chelate and concentration. Calcium, Mg, P, Cu, and Zn slightly slow down the reaction. The recovery of both chelates is observed when pH increases. The reaction is quick and practically complete in absence of competing ions, although the percentage of recompound chelate is affected by the chelating agent and pH. FeEDDHMA recompounds in a larger extension than FeEDDHA. The percentage of recompound chelate increases from pH 4 to 7. T...

Optimization of the addition of FeEDDHA to calcareous soils.

Abstract We have obtained an empirical equation, C

Effect of temperature on the kinetics of FeEDDHA sorption on a calcareous soil

= bCo cta, to describe behaviour of FeEDDHA in calcareous soils. Parameter “c”; of the previous equation remains practically constant from one soil to another, while parameters “b”; and “a”; have a lineal variation according to the carbonate content of the soils, which allows us to propose the following equation: Cs = (3.42 ‐ 0.043 CO3)Co 0‐91 t(0.007 CO3 ‐ 0.23) which is appropiate for calcareous soils in the South‐East of Spain (%C03>, 30).