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Accueil du site → Doctorat → Espagne → 2007 → Efecto de la alfalfa (Medicago sativa L.) y del abonado nitrogenado en el maíz (Zea mays L.) y el trigo (Triticum aestivum L.) en una rotación Alfalfa-Maíz-Trigo en redadío

Universitat de Lleida (2007)

Efecto de la alfalfa (Medicago sativa L.) y del abonado nitrogenado en el maíz (Zea mays L.) y el trigo (Triticum aestivum L.) en una rotación Alfalfa-Maíz-Trigo en redadío

Ballesta Remy, Astrid

Titre : Efecto de la alfalfa (Medicago sativa L.) y del abonado nitrogenado en el maíz (Zea mays L.) y el trigo (Triticum aestivum L.) en una rotación Alfalfa-Maíz-Trigo en redadío

Auteur : Ballesta Remy, Astrid

Université de soutenance : Universitat de Lleida.

Grade : Doctor Ingeniero Agronomico 2007

In agricultural systems, nitrogen (N) has always been the fertilizer element with an outstanding role. The complexity of its cycle and the different crop management systems difficult the planification of its availability for the plants. On the other hand, excessive or inadequate N applications can produce environmental problems and a lowest economic profitability. In the case of corn (Zea Mays L.), a particularly N demanding crop, it is important to synchronize contributions and N availability in the soil with plant demands. In the N Vulnerable Areas, contribution control become essential. The positive effects of the rotations of cultures are well known. To be more specific, benefits of the alfalfa (Medicago sativa L.) on the following crops are related principally to the ability of leguminous plants to fix atmospheric N2. One way to evaluate alfalfa’s N contribution is calculating its Nitrogen- Fertilizer Replacement Value (N-FRV). This thesis studies the effect of alfalfa in the corn and, later, in the wheat (Triticum aestivum L.) in a rotation Alfalfa-Corn-Wheat. Simultaneously, the effect of the N fertilizer is studied in a monoculture corn for three consecutive years in the same plot. The study was carried out between 1994 and 1997 in Torregrossa (irrigated area of Canal d’Urgell- Lleida-Spain). During three consecutive years, four doses of N fertilizer were applied (0, 100, 200, 300 kg N ha-1) in corn, cv. Juanita. These three years of monoculture are studied in Chapter I. During the first two years, simultaneously, alfalfa was cropped in half part of the block. The third year, alfalfa was replaced with corn, testing the same doses of fertilizer as in the monoculture. Then, corn in rotation with alfalfa could be compared with the corn in the third year of monoculture. The fourth year wheat, cv. Cartaya, was sowed in all the plots and two doses of N (0 and 100 kg N ha-1) were applied. Here, it was possible to compare the rotation Alfalfa-Corn-Wheat with the Corn-Corn-Corn-Wheat. These two last crops are studied in the Chapters II and III. In Chapter II a N-FRV of the alfalfa for two following crops in the irrigated area of the Ebro Valley is suggested. In Chapter III effects of alfalfa on the following crops and on the production conditions are studied. Every crop, the nitrate content in soil at three moments of the production period was determined. In corn, grain yield and its components, flowering and final biomass, height of plant, LAI and PARi, chlorophyll content in leaves, nitrate content in the base of the stem and N content in grain and plant were determined. Finally, nitrate content in the irrigation water and soil solution and organic matter content were followed. In wheat, grain yield and its components, stem elongation and final biomass and grain N content were measured. In monoculture, corn yield and plant growth were conditioned by initial level of nitrates in the soil, by N fertilizer amount and by nitrates contribution from irrigation water. Grain yield adjust to linear-plateau model in 1994 and 1995 and to quadratic-plateau model in 1996. Maximum yields, 10,2 Mg ha-1 in 1994, 13,1 Mg ha-1 in 1995 and 14,3 Mg ha-1 in 1996, were obtained with 100 kg ha-1 in 1994 and 1995 and with 200 kg ha-1 in 1996. With higher doses, corn kept on absorbing N that was accumulated firstly in the grain. The N-Fertilizer Replacement Value (N-FRV) of an alfalfa of two years in the conditions of the trial was evaluated in 160 kg N ha-1 for the first corn after alfalfa. For the following wheat crop, it was 76 kg N ha-1. The effect of the alfalfa affected nitrate soil content, corn yield (14,7 Mg ha-1 in la rotation and 11,9 Mg ha-1 in monoculture), final biomass and N extractions. In the following wheat, alfalfa affected soil content, yield (6,4 Mg ha-1 after alfalfa and 5,2 Mg ha-1 after the monoculture), grain N content and biomass accumulated until stem elongation. Some rules to determine N fertilizer N needs in a corn after the alfalfa are suggested

Mots Clés : Crop rotations — Fertilizer equivalent – FRV – Maize — N fertilization — Corn — N contribution — Rotación de cultivos — Fertilización equivalente – Maíz — Abonado nitrogenado — Contribución en N — Rotació de cultius — Fertilització equivalent – Panís — Blat de moro — Adobat nitrogenat — Contribució en N – Prematuritat – Emocions — Satisfacció

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