Vann og vanningsmetoder utfordringer i matproduksjon

Transkript

1 Vann og vanningsmetoder utfordringer i matproduksjon Johannes Deelstra Bioforsk Jord og vann

2 Befolkningsvekst og behov for mer mat 9,2 6,2 Store deler av verdens matproduksjon foregår ved hjelp av kunstig vanning (irrigation) Vi hører stadig mer om knapphet på vann.

3 Vannforbruk Matproduksjon er den største forbruker av a vann. For å produsere en balansert diett; I gjennomsnitt trenges det 3 4 m 3 med vann for å skaffe oss 3000 kcal/dag/person Som er cirka 70 ganger mer enn de 50 l/dag/person til daglig bruk Jordbruket bruker cirka 69% av de globale vannforsyninger, 21 % går til industrielle formål mens 10% går til husholdninger.

4 Hvor mye vann trenges for å produsere mat? Noen eksempler Bygg, hvete trenger cirka 1300 liter vann per kg Ris trenger cirka 3400 liters En brød skive krever 40 liter med vann, med ost kommer du på 90 liter 1 kg med kjøtt krever cirka liter med vann En dongeri bukse og T-shirt krever henholdsvis cirka og 2500 liter vann

5 Områder med knapphet på vann

6 ClimaRice I samarbeid med International Pacific Research Center (Hawaii) og Tamil Nadu Agricultural University (Sør-India) har Bioforsk satt i gang et omfattende klimaprosjekt, ClimaRice ( ). Hovedfokus er på effekt og tiltak knyttet til klimaendringer og risproduksjon i Cauvery River Basin, Tamil Nadu, India. Prosjektet finansieres av Utenriksdepartementet gjennom den norske ambassaden i New Delhi.

7 CLIMAWATER - Climate Change Impacts on River Basins in Semi-arid Areas in India The main goal; to prepare the base line scenarios and develop adaptation methods/tools that will help address the climate change impacts on hydrological regimes. Joint project by Bioforsk and IIT Delhi to be implemented in the Godavari River Basin. Prosjektet finansieres av Utenriksdepartementet gjennom den norske ambassaden i New Delhi The ambitions of the India s National Water Mission ( 2008) To improve WUE by 20%! How can this be achieved?

8 Hva må gjøres?? Vi må øke den såkalte Water Use Efficiency, produsere More crop per drop, flere kilo produkt per liter eller m 3 brukt vann. Defined as WUE = crop yield( kg) 3 water use( m ) How to improve the WUE Either by reducing the amount of water used or Increase the yield per unit water used

9 Improving WUE by changing irrigation methods Different irrigation methods have different efficiencies Border/furrow irrigation Application efficiency (E a ) in the order of 60 % E a = vekst fordamping vann tilført

10 Sprinkler, drip irrigation Application efficiencies (E a ) in the order of 80 % 90 % pws.byu.edu/pas100/irrigati.htm

11 Improving WUE by reducing the losses in the distribution system Losses to uneven water use along the canal (upstream/downstream problem) Direct losses into open drains Direct losses from canals Losses due to deep percolation/past root systems Evaporation from canals The canal conveyance efficiency (e c ) Earthen canals Lined canals Canal length Sand Loam Clay Long (> 2000 m) Medium ( m) Short (< 200 m)

12 Improving WUE by improving irrigation systems The overall irrigation scheme efficiency (e o ) combines the irrigation efficiencies A scheme irrigation efficiency of 50-60% is good; 40% is reasonable, while a scheme irrigation efficiency of 20-30% is poor. It is not unusual to have overall irrigation efficiencies in the order of 40%.

13 Improving WUE by improving irrigation systems/climawater project

14 Lift irrigation from main river, WUE studies borehole

15 Borehole surface irrigation, paddy/sugarcane Borehole, rice/paddy irrigation

16 Borehole drip irrigation 2 boreholes, 120 and 200 ft resp.

17 Improving WUE by improving irrigation systems However!!!! 1. before setting out on improving irrigation systems, a good overview of present use is necessary because 2. Inefficient use of water for agricultural production at one location might at present be beneficial for others users located downstream or be of use for ecosystem maintenance. (Deep) percolation losses do recharge groundwater being used for tubewell irrigation (in the case of India) Tail end losses flow back to the river to be used downstream

18 Agronomic practices and Water Use Efficiency Improvement of harvest index (ratio of marketable grain yield to crop biomass) However for most crops the limits are reached Agronomic practices Improvement of soil fertility, optimal fertiliser application, avoid land degradation, control plant diseases, tillage measures (mulching) Genetically modified crops (drought/pesticides resistance, less fertiliser mm) Introduction of new varieties or different irrigation methods to similar crops System of Rice Intensification (SRI) Introduction of new variety (Nerica/Warda)

19 System of rice intensification (SRI) SRI seedlings are very widely spaced compared with seedlings planted with traditional methods. With SRI, seedlings are planted when they are 8 to 15 days old, when there are just two leaves. With traditional methods, seedlings are planted when they are several weeks old. The seedlings shown at the left are 31 days old. Savings yields can double or more with only half as much water, the WUE is greatly increased (WUE) important when water becomes scarce; environmental benefits Reduced demand for water frees up water for other uses. Unflooded paddies do not produce methane, one of the major "greenhouse gases" that are contributing to global warming. There can be more nitrous oxide from unflooded paddies, which offsets to some extent the gains from reducing methane emissions,

20 Knapphet på vann og klima endringer Eksisterende mønster i nedbør viser seg å endre. Dette forringer forholdene for å produsere mat. Usikkerhet i nedbør; kommer det, det kommer seinere, det kommer med stor intensitet. 500 Rainfall (mm) Normal Std week

21 Vann og vanningsmetoder utfordringer i matproduksjon Klimaendringer/tørke truer Indias landbruk. India har i år vært rammet av omfattende tørke. En forsinket sommermonsun forårsaket at avlinger i store deler av landet tørket bort Arbeidet med å øke utnyttelsesgrade av vannet i jordbruk blir høyt prioritert.

22 Takk for oppmerksomhet Husk 1 kopp kaffe krever 140 liter med vann