Simulating the effects of different potassium and water supply regimes on soil water content and water table depth over a rotation of a tropical Eucalyptus grandis plantation

Christina Mathias, Le Maire Guerric, Nouvellon Yann, Vezy Rémi, Bordon B., Battie Laclau Patricia, Gonçalves José Leonardo M., Delgado-Rojas Juan Sinforiano, Bouillet Jean-Pierre, Laclau Jean-Paul. 2018. Simulating the effects of different potassium and water supply regimes on soil water content and water table depth over a rotation of a tropical Eucalyptus grandis plantation. Forest Ecology and Management, 418 : 4-14.

Quartile : Q1, Sujet : FORESTRY

Résumé : Although large amounts of potassium (K) are applied in tropical crops and planted forests, little is known about the interaction between K nutrition and water supply regimes on water resources in tropical regions. This interaction is a major issue because climate change is expected to increase the length of drought periods in many tropical regions and soil water availability in deep soil layers is likely to have a major influence on tree growth during dry periods in tropical planted forests. A process-based model (MAESPA) was parameterized in a throughfall exclusion experiment in Brazil to gain insight into the combined effects of K deficiency and rainfall reduction (37% throughfall exclusion) on the water used by the trees, soil water storage and water table fluctuations over the first 4.5 years after planting Eucalyptus grandis trees. A comparison of canopy transpiration in each plot with the values predicted for the same soil with the water content maintained at field capacity, made it possible to calculate a soil-driven tree water stress index for each treatment. Compared to K-fertilized trees with undisturbed rainfall (+K+W), canopy transpiration was 40% lower for K deficiency (−K+W), 20% lower for W deficit (+K−W) and 36% lower for combined K deficiency and W deficit (−K−W) on average. Water was withdrawn in deeper soil layers for −W than for +W, particularly over dry seasons. Under contrasted K availability, water withdrawal was more superficial for −K than for +K. Mean soil water content down to 18 m below surface (mbs) was 24% higher for −K+W than for +K+W from 2 years after planting (after canopy closure), while it was 24% lower for +K−W and 12% lower for −K−W than for +K+W. The soil-driven tree water stress index was 166% higher over the first 4.5 years after planting for −W than for +W, 76% lower for −K than for +K, and 14% lower for −K−W than for +K+W. Over the study period, deep seepage was higher by 371 mm yr−1 (+122%) for −K than for +K and lower by 200 mm yr−1 (−66%) for −W than for +W. Deep seepage was lower by 44% for −K−W than for +K+W. At the end of the study period, the model predicted a higher water table for −K (10 mbs for −K+W and 16 mbs for −K−W) than for +K (16 mbs for +K+W and 18 mbs for +K−W). Our study suggests that flexible fertilization regimes could contribute to adjusting the local trade-off between wood production and demand for soil water resources in planted forests.

Mots-clés Agrovoc : Eucalyptus, plantation forestière, potassium, enracinement, besoin en eau, croissance, stress dû à la sécheresse, évapotranspiration, fertilisation, transport des substances nutritives

Mots-clés géographiques Agrovoc : Brésil

Mots-clés libres : Water resources, Groundwater, Brazil, Eucalyptus, Deep roots, Nutrients

Classification Agris : K10 - Production forestière
F04 - Fertilisation

Champ stratégique Cirad : Axe 1 (2014-2018) - Agriculture écologiquement intensive

Auteurs et affiliations

• Christina Mathias, CIRAD-PERSYST-UPR AIDA (REU) ORCID: 0000-0003-3618-756X - auteur correspondant
• Le Maire Guerric, CIRAD-PERSYST-UMR Eco&Sols (BRA) ORCID: 0000-0002-5227-958X
• Nouvellon Yann, CIRAD-PERSYST-UMR Eco&Sols (THA) ORCID: 0000-0003-1920-3847
• Vezy Rémi, CIRAD-PERSYST-UMR Eco&Sols (FRA) ORCID: 0000-0002-0808-1461
• Bordon B., ESALQ (BRA)
• Battie Laclau Patricia, CENA (BRA)
• Gonçalves José Leonardo M., USP (BRA)
• Delgado-Rojas Juan Sinforiano, UNIFESP (BRA)
• Bouillet Jean-Pierre, CIRAD-PERSYST-UMR Eco&Sols (MDG)
• Laclau Jean-Paul, CIRAD-PERSYST-UMR Eco&Sols (FRA) ORCID: 0000-0002-2506-214X

Source : Cirad-Agritrop (https://agritrop.cirad.fr/586780/)

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