Carlos Zaragoza

Effect of Biodegradable Mulch Materials on Weed Control in Processing Tomatoes

Abstract Three years of field trials have been carried out in Zaragoza, Spain, using different biodegradable mulch materials in processing tomatoes. The aim was to evaluate weed control with several biodegradable mulches as alternatives to black polyethylene (PE) mulch. The treatments were rice straw, barley straw, maize harvest residue, absinth wormwood plants, black biodegradable plastic, brown kraft paper, PE, herbicide, manual weeding, and unweeded control. Assessments focused on weeds and on crop yield. A laboratory study showed that 1 kg/m2 of organic mulch was sufficient to cover the soil for rice, barley straw, and maize harvest residue. The most abundant weed species in the field were purple nutsedge, common purslane, common lambsquarters, and large crabgrass and a change in weed composition was observed between treatments and years. Most weed species were controlled by the mulching materials except that purple nutsedge was controlled only by paper mulch. The other species were well controlled by PE and biodegradable plastic and also by some of the organic mulch treatments. Best weed control and lowest weed biomass were achieved by paper followed by PE and biodegradable plastic. The best organic mulch was rice straw and the worst weed control was from absinth wormwood. Tomato yield was highest for PE followed by paper, manual weeding, biodegradable plastic, and rice straw and was clearly related to weed control. Paper, biodegradable plastic, and rice straw are potential substitutes for PE and herbicides. Nomenclature: Common lambsquarters, Chenopodium album L. CHEAL; common purslane, Portulaca oleracea L. POROL; large crabgrass, Digitaria sanguinalis L. Scop. DIGSA; purple nutsedge, Cyperus rotundus L. CYPRO; absinth wormwood, Artemisia absinthium L.; barley, Hordeum vulgare L.; maize, Zea mays L.; rice, Oryza sativa L.; tomato, Lycopersicon esculentum Mill. ‘Perfect Peel’.

Economic evaluation of cereal cropping systems under semiarid conditions: minimum input, organic and conventional

Cropping systems like organic farming, selling products at a higher price and promoting environmental sustainability by reducing fertilizer and pesticides, can be more profitable than conventional systems. An economic evaluation of three cropping systems in a seven year period experiment was performed, using a common rotation (fallow-barley-vetch-durum wheat) in a semi-arid rainfed field of Spain. The minimum input system included mouldboard ploughing, cultivator preparation, sowing and harvest. The conventional system involved mineral fertilizer and herbicide treatments, while the organic system involved composted manure and mechanical weed control. The resulting economic margins were highest with the minimum input system, followed by the organic and conventional systems. If the cereal grain from the minimum input system was sold at a higher price on the organic market, this system was the most profitable. Without the price difference, the organic system was as profitable as the conventional one.

Above-soil and in-soil degradation of oxo- and bio-degradable mulches: a qualitative approach

Degradable materials have been suggested to overcome accumulation in the field of persistent plastic residues associated with the increasing use of polyethylene mulches. New degradable materials have been proven successful for increasing crop productivity; however, their degradation in the field has been hardly addressed. A qualitative scale was used in the present study to assess the above-soil and in-soil degradation of degradable mulches during the cropping season. Degradation was determined in three biodegradable plastic mulches (Biofilm, BF; Mater-Bi, MB; Bioflex, BFx), two paper sheet mulches (Saikraft, PSA; MimGreen, PMG) and one oxo-degradable plastic mulch (Enviroplast, EvP). Polyethylene (PE) mulch was used as control. Mulches were tested in five Spanish locations (Castilla-La Mancha, La Rioja, Navarra, Aragon and Catalunya), with three crop seasons of processing tomato. Biodegradable plastic mulches BF and MB degraded more and faster above-soil than paper mulches; among biodegradable mulches BF degraded more than MB, and MB more than BFx. The above-soil degradation of the oxo-degradable mulch EvP was highly dependent on location and crop season, and it degraded more than PE. Main environmental factors triggering above-soil degradation were radiation, rainfall and crop cover. In-soil, paper mulches and BF degraded more and faster than MB, whereas BFx and EvP barely degraded. Environmental factors triggering in-soil degradation during the crop season were rainfall and irrigation water. The effect of soil parameters (organic matter, nutrient availability) on degradation during the cropping season was not evidenced. The qualitative scale used proved convenient for determining mulch field degradation. A visual scale for supporting the qualitative evaluation is provided. In order to standardise parameters and criteria for future studies on field mulching degradation evaluation, a unified degradation qualitative scale is suggested.

Organic Versus Conventional Methods of Fertilization and Weed Control in a Long Term Rotation of Cereals in Semiarid Spain

Under semiarid conditions the response of cereal crops to chemical fertilizers and weed control practices with herbicides is often reduced. In fact, the economic profitability of agricultural production in many dryland regions is critically affected by high costs of inputs and low crop yields. As a solution, cropping systems like organic farming, obtaining similar yields and promoting environmental sustainability by reducing fertilizer and herbicides, could be an alternative to conventional systems. In this study, 23 trials were performed in five semiarid regions of Spain during 5 yr to compare different fertilizers and weed control methods on durum wheat (Triticum durum Desf.) and barley (Hordeum vulgare L.) yields. The following rotation pattern was developed on the experimental plots: fallow-barley-ground ploughed vetch (Vicia sativa L.)-durum wheat. Plots either received organic fertilizer, chemical fertilizer, or no fertilizer. In addition, three levels of weed control were applied in cereal plots: flex-tine harrow tillage, conventional herbicide, and no weeding. The results indicated that neither the fertilization nor the weed control have effect on the yield crop.

Influence of fruit ripeness at the time of seed extraction on pepper (Capsicum annuum) seed germination

Abstract The influence of fruit ripeness (half ripe, fully ripe, overripe) at the time of seed extraction on seed germination behaviour, at 25 °C and 13 °C, was studied in two Spanish pepper cultivars for canning. Seeds from half ripe fruits had a poorer behaviour than those taken from fully ripe fruits, especially at 13 °C. Room ripening and overripening of half ripe fruits improved the germination behaviour of the seeds although this behaviour was poorer than that of seeds extracted from fully ripe fruits that were allowed to overripen. Overripening of fully ripe picked fruits slightly improved germination behaviour.

Tolerance of Direct-Seeded Paprika Pepper (Capsicum annuum) to Clomazone Applied Preemergence1

Abstract: Field experiments were conducted from 1997 to 1999 at Ejea and at Valdegon (Spain) to study weed control and tolerance of direct-seeded pepper ‘Agridulce SIA’ to clomazone alone or with linuron, napropamide, or pendimethalin. The main weeds at Ejea were redroot pigweed, Diplotaxis erucoides, common purslane, and ivyleaf speedwell, while at Valdegon they were Solanum physalifolium and common purslane. Pepper was tolerant to clomazone applied at 0.18 kg ai/ha, but weed control was less than 77%. Increasing the rate of clomazone to 0.36 kg/ha controlled weeds at least 85% and did not injure pepper. Clomazone at 0.54 and 0.72 kg/ha injured pepper 6 wk after planting (WAP), but plants recovered and the dry weight and yield of paprika were not affected. Napropamide at 2.03 kg ai/ha applied with clomazone improved the control of D. erucoides. Addition of pendimethalin at 0.17 to 0.25 kg ai/ha to clomazone did not improve weed control and increased pepper injury 6 WAP in 1 of 2 yr, but yield was not affected. Linuron at rates ranging from 0.08 to 0.13 kg ai/ha used in combination with clomazone provided complete weed control but injured pepper the most (34 to 88%) and reduced pepper stand by 50% in 1 yr. Nomenclature: Clomazone; linuron; napropamide; pendimethalin; common purslane, Portulaca oleracea L. #3 POROL; Diplotaxis erucoides (L.) DC.; ivyleaf speedwell, Veronica hederifolia L. # VERHE; redroot pigweed, Amaranthus retroflexus L. # AMARE; Solanum physalifolium Rusby; paprika pepper, Capsicum annuum L., ‘Agridulce SIA’. Additional index words: Weed control, Convolvulus arvensis, CONAR. Abbreviations: PRE, preemergence; WAP, weeks after planting.

Experiments on mechanical weed control in saffron crops in Spain

In the Jiloca valley (Teruel, Spain) saffron (Crocus sativus) is attracting attention because of its high quality and the growing demand in the gourmet market. To increase production the phytosanitary status needs to be guaranteed as well as the mechanization of the basic agronomic practices, especially weed control operations. Saffron is a perennial crop and weeding is especially important after flowering in mid of October until May when the aerial part disappears. Eight field trials were established to test the effect of flextine harrow, torsion and finger weeders. Torsion and finger weeders were difficult to adjust due to compact soils and steering problems. Efficacy for these tools was higher than 80% in two out of 12 occasions, only, while the flex-tine harrow exceeded this value in 7 occasions out of 18. The flextine harrow did no require adjustments on the row and could be used in an aggressive position because of the 20 cm plantation depth of the corms. Weeds including the Poaceae Lolium rigidum could be effectively controlled with the flextine harrow provided climatic conditions allowed treating immediately after flower harvest. Saffron flower and corm density were reduced by more than 40% after 3 cropping seasons without weed control compared to harrowing. Only slight differences were found in bulb size being higher for the harrowed plots. The use of the flex-tine harrow is highly recommended to reduce yield losses as well as to avoid weeds hosting viruses.