Canarygrass (Phalaris canariensis L.) crops are sown from June to mid-September in the southeastern area of the province of Buenos Aires, Argentina. Sowing dates in this range result in different growing temperatures and photoperiods that affect the duration of developmental stages, biomass production, and seed yield and its components. For Argentina, there are no reported studies that address these effects. This study on the effects of sowing date was conducted during four growing seasons (1996–1999) at the Instituto Nacional de Tecnologí a Agropecuaria (INTA) Experimental Station at Balcarce, Argentina, using a population provided by Dr. Jaime Lloveras, University of Leyda, Spain. Different seeding dates were chosen from June to mid-September. The experiment was a randomized complete block design with four blocks. When the sowing date was delayed, total dry matter (DM) decreased. For early sowing dates seed yield was constant, but after 10 August it was reduced by 1.5% for each day of delay. Earlier sowing increased the duration of pre-anthesis development with greater uniformity in panicle size and the number of seeds. Seed yield was related lin early to the number of seeds and plant dry matter yield (DMY). The rate of progress from emergence to anthesis (1/days from emergence to anthesis) was proportional to the mean photoperiod. Under the environmental conditions in Balcarce, the accumulated required thermal units for anthesis was reduced when sowing was delayed from June to September. This reduction was related to the photoperiod and was estimated as –189.3 growing degree-days per hour of photoperiod increment. Key words: Canarygrass, seed yield, sowing date, yield components

En este trabajo, se describe el proceso de compostaje mediante pilas volteadas de la fracción orgánica, recogida selectivamente, de residuos sólidos urbanos (RSU), analizado durante tres años. El compost, aceptable para su uso agrícola, fue aplicado en cultivos de trigo y ajo, combinando tratamientos mixtos con el objetivo de conocer que tipo de fertilización era la que generaba los mejores resultados, y demostrar como la fertilización orgánica puede llegar a ser una alternativa real en nuestros suelos con los consiguientes beneficios ambientales. No se encontraron incidencias de metales sobre los frutos ni los suelos. La producción fue también semejante al control. A pesar de todo esto, en caso de aprobación de la nueva Normativa Europea que se encuentra en fase de discusión, y con las restricciones que se pretenden imponer, el compost de RSU fabricado en la ciudad de Córdoba (España) tendrá grandes dificultades para su uso agrícola si se continúan con las mismas prácticas de gestión debido a su alto contenido en metales.

Compost made from municipal solid waste (MSW) contains heavy metals that can interfere with the use of organic amendment in soil. In order to find effective ways to reduce the potential risk of heavy metals, we have investigated a novel approach by use of organic acid during MSW composting. Citric and oxalic acid dissolutions (0.25 mol x (-1)) were used at determined ratios (kg dried MSW: cm(3) acid). Cr and Ni concentrations were similar in compost, independent of acid contribution. By contrast, Cu concentrations decreased by 63% (at citric acid ratio 1:15), 65% (at citric acid ratios 1:20 and 1:40) and 83% (at oxalic acid ratio 1:40); furthermore, Pb concentrations reduced by 71% (at citric acid ratios 1:20 and 1:40 and at oxalic acid ratio 1:40) and Zn concentrations reduced by 67% (at citric acid ratios 1:10 and 1:20) and 70% (at oxalic acid ratio 1:40). The total metal mass decreased by an average of 12% in the compost fraction, whereas the total percentage of the residual fraction increased by an average of 20%. The acid addition in the studied ratios improved compost quality without negatively influencing biostabilization.

IntroductionThe commercially viable cultivation of canary grass (Phalaris canariensis L.) in Argentina arose at the beginning of this century. Little attention has been paid to improving the species genetically, which has resulted in a lack of commercial varieties. Growers generally use seeds from their own production or that of other growers. Seeds are obtained from seed gathers, and in most cases these gathered seeds contain a mixture of different populations. In other countries a range of cultivars are present, even though there has been little genetic improvement. In this study, the introduced varieties of canary grass cv. Elias and cv. Keet, orginally from the United States, were compared with local populations of canary grass in Argentina.

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