MURILLO José M., CABRERA Francisco, LÓPEZ Rafael, VÁZQUEZ Benjamín.

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1 Scientific registration nº 385 Symposium nº 40 Presentation: poster Humic amendment derived from alpechin compost. A worthwhile liquid organic fertilizer Amendement humique obtenu à partir du compost d alpechin. Un fertilisant organique liquide intéressant MURILLO José M., CABRERA Francisco, LÓPEZ Rafael, VÁZQUEZ Benjamín. Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS - CSIC), P.O.Box Seville, Spain. INTRODUCTION The production of olive oil in Andalucía (S Spain) is ca. 20 of the total from the Mediterranean region. The olive oil processing industry produces alpechín (a wastewater) at a rate of ca L kg -1 of olive (ca m 3 year -1 ). The disposal of alpechín is a serious problem because of its high organic load and salt content. Since in 1981, the Spanish Government prohibited the discharge of alpechín into the rivers and subsidized the construction of ponds for its storage and drying, around 1000 evaporation ponds have been constructed in Andalucía (Cabrera et al. 1997). The olive mill sludge obtained from ponds can be composted with other plant residues to produce a high quality compost for agriculture (Cabrera et al., 1990). A liquid humic amendment may also be obtained from the alpechín compost by further moistening and fermentation. The present study deals with the effect of this humic amendment (Fertiormont ) on growth and nutritional status of a ryegrass and on selected soil properties after the experiment. MATERIALS AND METHODS The assay was carried out in a greenhouse, using pots of about 1.5 kg of dry soil. The first horizon of a light yellowish-brown sandy clay loam Xerochrept typical of SW Spain (ph 7.9, CaCO 3 25, OM 0.5) was used as a substrate, after grinding to a particle size of 2mm. The liquid humic amendment Fertiormont (F, Table 1) was used as organic fertilizer. A complex 15N-15P 2 O 5-15K 2 O inorganic fertilizer was mixed with the soil (0.32 g fertilizer/pot) to establish four fertilizing treatments: irrigation with deionized water (inorganic fertilizer treatment, IF), and irrigation with solutions of water/f at ratios of 1/200, 1/100 and 1/25 (LF, MF and HF treatments, respectively). Soil without any fertilizer was used as a control (treatment C). The sowing was set up with 1g of seeds per pot of Lolium multiflorum Lam. cv. Tewera. Three replicates per treatment (15 pots in total), randomly arranged in a complete block design, were established. Six irrigations 1

2 per pot were carried out to complete a total amount of 700ml of deionized water or the corresponding F solution. Table 1. Analysis of Fertiormont (F) Electrical conductivity (ds m -1 ) 11.6 Total P ( ) 1100 Dry matter (, w/w) 41.7 Total K ( ) Ashes (, w/w) 6.6 Total Ca ( ) 2200 Organic matter (, w/w) 35.0 Total Mg ( ) 500 Total humic extract (, w/w) 29.2 Total Fe ( ) 3670 Humic acids (, w/w) 1.5 Total Cu( ) 3.5 Fulvic acids (, w/w) 27.7 Total Mn ( ) 34 N-Kjeldahl (, w/w) 0.96 Total Zn ( ) 8.0 C/N ratio 12.3 Total Na ( ) 900 Ryegrass was harvested three times at monthly intervals from sowing, recording plant fresh and dry weight for each pot (by drying at 70 o C for 48 h). After grinding, plant material was analyzed for N-Kjeldahl, and mineral elements were analyzed following dry ashing and dissolution in HCl as described by Jones et al. (1991). After the last ryegrass harvest, a germination bioassay for cress (Lepidium sativum L.) and ryegrass was set up using 3g soil from each treatment (40 moisture) in Petri dishes (5.5 cm diameter) lined with a filter paper (Whatman no. 1) (Murillo et al., 1995). Five dishes per treatment and species (five seeds per dish) were randomly arranged in the dark at room temperature. Germinated seeds and root length were recorded after 48 h, and a germination index (GI) was obtained for each species by multiplying the germination percentage by the root length percentage divided by 100. The soil of each treatment was analyzed for ph and electrical conductivity (soil:water ratio of 1:5), oxidizable organic matter (OM), N-Kjeldahl, P-Olsen, K-acetate (ph 7), and DTPA extractable Fe, Mn, Zn and Cu (Lindsay and Norvell, 1978). The soil of C, IF, and HF treatments was also analyzed for urease, phosphatase, arylsulphatase, β-glucosidase, and dehydrogenase activities (Tabatabai, 1982). RESULTS AND DISCUSSION The total humic extract of F, ca. 30, is twofold the minimum established by Spanish legislation (BOE nº 146, 19/06/91) for a product to be considered a liquid humic amendment. However, despite its promising effects on plant growth and soil properties, it might be advisable to try to increase its humic acids concentration, which is only 1.5 (Table 1). The accumulation of F in the soil (leaching was prevented) had a positive effect on ryegrass growth. The dry matter yielded in the third cut in the MF and HF treatments was significantly greater than that of the IF treatment. The HF treatment yielded the maximum total dry matter production, the differences with those of the other treatments being strongly significant (P << 0.05). In addition, F accumulation tended to increase plant moisture content, not only in relation to the control (C), but also in relation to the IF treatment (Table 2). This would be a consequence of the enhanced plant nutrient uptake, especially N (Bailey, 1973), resulting from F application. 2

3 Table 2. Mean values per pot of dry matter (DM) and moisture (M) of ryegrass Treatment 1st cut 2nd cut 3rd cut Total DM DM (g) M () DM (g) M () DM (g) M () (g) C 0.39 a 88.4 a 0.62 a 80.4 a 0.12 a 82.6 a 1.13 a IF 1.50 b 90.1 b 0.94 b 85.5 b 0.22 ab 84.2 ab 2.66 b LF 1.46 b 90.2 b 0.92 b 87.2 cb 0.30 bc 85.4 ab 2.69 b MF 1.40 b 90.5 b 0.90 b 88.2 cd 0.41 c 87.3 b 2.59 b HF 1.47 b 90.3 b 1.42 c 89.4 d 1.01 d 87.4 b 3.89 c Ryegrass N and K increased in the F treatments from the first cut, compared with the C and IF treatments; Ca and Na showed in general the opposite trend. The most surprising effect was on the Mn concentration, which exceeded four times that of the control in treatment HF (2nd and 3rd cuts, Table 3). Magnesium concentration (data not shown) showed in general little variation between treatments. Table 3. Ryegrass analysis (mean values from dry matter) Treatment N P K Ca Na Fe Mn Zn Cu 1st cut C 1.72 a 0.19 a 4.87 a 1.13 c 0.39 b 161 b 99 a 65 b 11 a IF 2.35 b 0.37 b 5.97 b 0.98 b 0.41 b 118 a 75 a 25 a 11 a LF 2.35 b 0.38 b 7.24 c 0.90 a 0.25 a 131 a 166 b 146 c 12 a MF 2.37 b 0.36 b 7.14 c 0.87 a 0.25 a 121 a 219 cb 65 b 11 a HF 2.41 b 0.26 a 6.96 c 0.94 b 0.24 a 161 b 269 c 47 b 12 a 2nd cut C 0.71 a 0.13 a 2.83 a 1.96 c 0.17 b 108 a 118 a 14 a 5.3 a IF 1.07 b 0.32 b 4.36 b 1.44 b 0.13 a 285 ab 159 a 32 b 26 b LF 1.40 c 0.43 d 5.56 c 1.54 b 0.10 a 377 b 420 b 42 cb 25 b MF 1.70 d 0.45 d 5.92 d 1.26 b 0.12 a 274 ab 545 c 45 c 32 b HF 2.24 e 0.39 c 6.89 e 0.93 a 0.11 a 183 a 539 c 39 cb 28 b 3rd cut C 1.06 a 0.18 a 2.03 a 1.35 b 0.28 b 50 a 82 a 45 a 9.0 a IF 1.06 a 0.33 b 3.20 b 2.16 c 0.32 b 282 c 159 b 47 a 9.0 a LF 1.38 b 0.36 c 4.19 c 1.60 b 0.25 a 301 c 187 b 44 a 6.0 a MF 1.63 c 0.51 d 4.49 c 0.99 a 0.29 a 120 b 196 b 69 b 10 b HF 1.88 d 0.38 c 5.86 d 0.79 a 0.24 a 122 b 328 c 110 c 12 b Values followed by the same letter in the same column (for each cut) do not differ significantly (P < 0.05). From Tables 2 and 3, it can be deduced that the HF treatment led to a strong synergism in the uptake of N, K, and Mn (and Zn in the 3rd cut), since their concentrations and accumulations increased (significantly, in general, in comparison with the other treatments) at the same time as the biomass increased. In the case of P and Ca, a dilution effect could be present, with Na and Fe showing the same tendency. Except for Na and Zn, the HF treatment yielded the highest above-ground nutrient accumulations (Table 4), N, K, and Mn generally showing the greatest increases. 3

4 Nitrogen, K, and Mn (besides OM, P, and Fe) were significantly (P < 0.05) increased in the soil by the HF treatment, compared with the other treatments (Table 5). This, among other factors, could influence the observed enhanced plant nutrient uptake. Except for P, LF and MF treatments also tended to increase the above mentioned soil parameters, compared with the C and IF treatments, the differences being significant in same cases. Table 4. Total nutrient accumulations per pot in ryegrass (three cuts, mean values from dry matter) Treatment N P K Ca Na Fe Mn Zn Cu C 12.4 a 1.8 a 38 a 18.2 a 2.9 a 0.14 a 0.12 a 0.04 a 0.01 a IF 47.6 b 9.3 b 138 b 33.0 b 8.1 c 0.51 b 0.30 a 0.26 b 0.04 b LF 51.3 b 10.7 b 170 b 32.1 b 4.8 b 0.63 c 0.69 b 0.26 b 0.04 b MF 55.0 b 11.3 b 172 b 27.3 b 5.8 b 0.47 b 0.88 b 0.16 b 0.05 b HF 81.1 c 13.3 c 259 c 35.2 b 6.3 b 0.62 c 1.50 c 0.24 b 0.07 c Table 5. Soil analysis after application of the treatments Treatment OM NKjeldhal POlsen Kacetate Fe-DTPA Mn-DTPA Zn-DTPA Cu-DTPA C 0.90 a a 1.4 a 125 a 4.09 a 11.9 ab 10.6 a 1.59 a IF 0.98 ab a 4.5 a 117 a 4.83 a 10.5 a 9.4 a 1.61 a LF 1.08 bc ab 5.0 ab 125 a 6.72 b 13.6 bc 15.6 b 1.81 b MF 1.19 dc b 4.3 a 163 a 8.65 c 14.2 c 14.9 b 1.69 ab HF 1.30 d c 8.7 b 462 b 24.30d 20.9 d 14.0 b 1.81 b It was also interesting that a high accumulation of F in the soil (HF treatment), significantly increased (P < 0.05) some soil enzyme activities in the treated soil (Table 6). Soil enzymes play an important role in soil microbial ecology by catalyzing innumerable reactions in soils, and considerable interest and effort has been devoted to including soil enzyme activities as a soil fertility and soil quality index (Dick, 1994). It has been verified that selected soil enzymes activities may correlate with crop yields better than does the sole microbial enumeration, although this relationship might be expected to be stronger in unmanaged or low-input systems. As pointed out by Dick (1994), high amounts of external inputs of nutrients and water can greatly stimulate plant growth without a corresponding response by soil microorganisms, and he cited an example in which soil respiration and enzyme activity increased in manure-amended soil, but soils amended with inorganic fertilizer showed lower biological activity. 4

5 Table 6. Soil enzyme activities for C (control), IF (inorganic fertilizer), and HF (high dose of F) treatments (µg g -1 h -1 ) Treatment Urease Phosphatase Arylsulphatase β-glucosidase Dehydrogenase C 125 a 50.3 a 99.7 b 34.9 a 2.15 a IF 101 a 79.1 b 11.0 a 47.4 a 1.13 a HF 141 a 90.2 c 122 c 114 b 9.50 b Treatment IF tended to decrease the assayed soil enzyme activities (Table 6), with a significant difference compared with C treatment in the case of arylsulphatase activity. However, despite the presence of the inorganic fertilizer, a high input of F restored (and significantly exceeded compared with IF and C treatments) all the assayed enzyme activities. This is important in connection with the increasing pressure for a judicious combination of mineral fertilizers with locally available organic sources to be used in a sustainable agriculture (Sequi, 1996). In the parameters analyzed in this study, the only potential constraint derived from the noticeable F accumulation in the soil was a significant increase in EC. HF treatment yielded an EC of 325 ds m -1, significantly greater (P < 0.05) than those of C (261 ds m -1 ), IF (264 ds m -1 ), LF (276 ds m -1 ), and MF (279 ds m -1 ). Electrical conductivity has frequently been included in the minimum data sets established for monitoring soil quality (Larson and Pierce, 1994), and, of course, soil fertility. Taking into account that F is a product with high EC and Na content (Table 1), the latter parameter being a better guide because determination of EC in organic products may be somewhat erratic, and its value may be strongly affected by products other than phytotoxics, F-treatment soils were used for a germination bioassay. This was carried out using not only ryegrass Tewera, but also cress (Lepidium), the latter species because of its sensitivity to toxic substances and its speed of germination (International Seed Testing Association, ISTA, 1985; Zucconi et al., 1985). The soil of C and IF treatments were also assayed for comparison (Table 7). Despite the increase in soil electrical conductivity caused by the HF treatment, germination and main root length of cress and ryegrass were not affected, showing that F, either applied at a high rate or heavily accumulated in the soil, does not affect critical parameters related to soil quality. Symptoms of toxicity are more pronounced at an early stage of root growth, and can cause root shortening, even at low concentrations (Zucconi et al., 1985). In this assay, the root length of ryegrass was basically the same in all treatments, and in the case of cress, the root length was even enhanced to a some extent by HF treatment (Table 7). In both cases, the GI values of treatments including F were similar to or greater than those of the control, and much greater than 60, the level at which the toxic phase of organic matter is considered to be terminated (Zucconi et al., 1985). In the case of cress, the presence of F seemed to overcome some depressant effect of the IF treatment. 5

6 Table 7. Cress (Lepidium) and ryegrass germination bioassays in the soil of the different treatments (GI, germination index). Species Treatment Germination of control Root length mm Root length of control GI Cress C 100 a 9.8 b IF 90 a 4.2 a LF 140 a 7.2 ab MF 120 a 7.2 ab HF 90 a 10.3 b Ryegrass C 100 a 3.8 a IF 200 a 4.1 a LF 160 a 4.5 a MF 120 a 4.7 a HF 180 a 4.3 a Values followed by the same letter in the same column (for each species) do not differ significantly (P < 0.05). The high dose of F applied in this experiment may be excessive for agricultural purposes, because the aim of an appropriate organic fertilizer management, in relation to N, is to maximize its apparent recovery fraction (Harmsen, 1984), through reducing losses and increasing the N availability to the crops. This fraction generally decreases with increasing rates of fertilizer applied (Harmsen, 1984), which could imply an increased risk of NO 3 -N pollution of groundwaters. In this experiment, the apparent recovery fraction for N (data not shown) decreased from 0.73 in IF treatment to 0.21 in HF treatment, reaching a reasonable value, 0.46, in LF treatment. Thus, it seems that a continuous, but judicious, application of F (for example, in fertigation) could enhance soil properties and plant nutrition in the long term, although soil Na should be periodically monitored. As pointed out above, an increase in the humic fraction of F would be desirable. REFERENCES Bailey, R.W Water in herbage. In: Chemistry and Biochemistry of Herbage (Eds. G.W. Buttler and R.W. Bailey), Vol 2, Acad. Press. London, UK. Cabrera, F.; López, R.; Murillo, J.M. and Breñas, M.A Olive vegetation water residues composted with other agricultural by-products as organic fertilizer. Proc. 10th World Fertilizer Congress of CIEC, , Nicosia, Cyprus. Cabrera, F.; López, R.; Martín-Olmedo, P. and Murillo, J.M Aprovechamiento agronómico de composts de alpechín. Fruticultura Profesional, 88 (special issue: Olivicultura II), Dick, R.P Soil enzyme activities as indicators of soil quality. In: Defining Soil Quality for a Sustainable Environment (Eds. J.W. Doran; D.C. Coleman; D.F. Bezdicek 6

7 and B.A. Stewart), SSSA Special Publication no. 35, , SSSA, ASA, Madison, Wisconsin, USA. Harmsen, K Nitrogen fertilizer use in rainfed agriculture. Fertilizer Research, 5, International Seed Testing Association (ISTA) International rules for seed testing. Rules Seed Sci. Technol. 13, Jones, J.B. Jr.; Wolf, B. and Mills, M.A Plant Analysis Handbook. Micro-Macro Publishing, Athens, Georgia, USA. Larson, W.E. and Pierce, F.J The dynamics of soil quality as a measure of sustainable management. In: Defining Soil Quality for a Sustainable Environment (Eds. J.W. Doran; D.C. Coleman; D.F. Bezdicek and B.A. Stewart), SSSA Special Publication no. 35, 37-51, SSSA, ASA, Madison, Wisconsin, USA. Lindsay, W.L. and Norvell, W.A Development of a DTPA soil test for Zn, Fe, Mn, and Cu. Soil Sci. Soc. Am. J. 42, Murillo, J.M.; Cabrera, F.; López, R. and Martín-Olmedo, P Testing low-quality urban composts for agriculture: germination and seedling performance of plants. Agriculture, Ecosystems and Environment, 54, Sequi, P The role of composting in sustainable agriculture. In: The Science of Composting (Eds. M. De Bertoldi, P. Sequi, B. Lemmes and T. Papi), Part 1, 23-29, Blackie Academic & Professional, London, UK. Tabatabai, M.A Soil Enzymes. In: Methods of Soil Analysis Part 2. Chemical and Microbiological Properties (Eds. A.L.Page; R.H. Miller and D.R.Keeney), Agronomy no. 9, , ASA, SSSA, Madison, Wisconsin, USA. Zucconi, F.; Monaco, A.; Forte, M and De Bertoldi, M Phytotoxins during the stabilization of organic matter. In: Composting of Agricultural and other Wastes (Ed. J.K.R. Gasser), 73-86, Elsevier Applied Science Publishers, London, UK. Keywords: humic amendment, raygrass growth, nutrients, chemical properties Mots clés: amendement humique, raygrass, croissance, nutrition, propriétés chimiques 7