Tree Soil Crop Interactions

Transcription

1 MK anskap erdesaan dan ertanian Tree Soil Crop Interactions Tim Dosen: rof. Dr. Hadi Susilo Arifin rof. Dr. Wahju Qamara Mugnisjah Dr. Kaswanto Tree Soil Crop Interactions Meine van Noordwijk Kurniatun Hairiah Departemen Arsitektur anskap rogram ascasarjana IB 2014 c Sun light itter itter Trees Negative effects a = shading b = root competition a a Crops b Trees itter ositive effects c = itter fall d = deep roots of trees act as safety-net itter d d d c Tree-soil-crop interactions Understanding tree-annual crop interactions strongly determines the results of the transition into agroforest: success or failure! The overall interactions can be positive (advantageous) or negative (disadvantageous). d Disadvantageous interactions Competition for light: shading by trees, reducing light intensity at crop level Competition for nutrient and water: shallow tree root systems are likely to compete with crops for nutrient and water, reducing uptake by crop roots. Trees can be a host for pests and diseases of annual food crops (or vice-versa). 1

2 Advantageous interactions itter fall and pruned leaves or small branches supply a protective litter layer and organic matter for the soil A litter layer reduces loss of water from the soil surface by evaporation and improves the soil moisture regime Shading by trees may suppress weed growth (e.g. Imperata cylindrica), and reduce the risk of fire spread in the dry season Deep tree rooting systems improve nutrient recycling by acting as a (1) nutrient safety- net, taking up nutrients which leach out to the subsoil, out of reach for the shallow rooted crops; and (2) nutrient pump, taking up nutrients released from mineral weathering in deeper layers egume trees t can biologically bi l i ll fix fi nitrogen it from f the th atmosphere t h (N2), and supply nitrogen to the soil that decreases the requirement for N fertilizer roviding a stable microclimate, by reducing wind speed, increasing air humidity, providing partial shade (for instance Erythrina in cacao or coffee gardens) eltophorum liricidia (Soga) (amal) 4m otential for root competition Root competition OR useful overlap?? Deep tree root systems act as nutrient pump or as a safety-net 2

3 Hedgerow intercropping during dry season Shading out weeds during dry season eltophorum in an Imperata field itterfall under eltophorum trees 3

4 Organic layer eucaena ~1.85 m Maize root systems orest soil Old tree root channel Agricultural soil profile Deep tree root systems as nutrient pump in fertile soil Shallow root system of eucaena Deep root system of eltophorum Maize root system Is Jackfruit a drought tolerant tree? 4

5 arameter Experimental treatments: Experimental treatment Shading Without canopy pruning With canopy pruning Competition of water Without root barrier and nutrient With root barrier Mulching Without mulch transfer With mulch transfer ong term residual Without tree removal effect With removal of complete hedgerows Total plot 8 sub plot per tree species How to quantify the interaction? Root barrier 5

6 Biomass transfer Biomass transfer 2X 1X Quantifying biomass of tree pruning Mulch treatment Tree removal Mulch transfer 6

7 Control plot ~ No hedgerows S.E.D 4 level N fertilization: No fertilizer 45 kg ha kg ha -1 rain yield, Mg ha N 90N 45N ong term residual 135 kg ha -1 0N Control Hedgerow intercropping 7

8 5 4 C rain yield, Mg g ha-1 Dry season Residual 3 / / 2 Control M l h Mulch 1 C 0 / R t Root C C / C / -1-2 / C -3 Shading C = Calliandra; C lli d = lemingia; = eltophorum; = liricidia; = eucaena N application, kg Hedgerow of pruned trees B Two years after tree removal Double Mulch application rom a biophysical point of view, agroforestry systems can only be beneficiary, runing biomass A Normal ha-1 if there is at least some complementarity in resource capture Aluminium toxicity 8

9 Terima Kasih 9