FU BerlinSoil F     Fertility Effect on Water Productivity of Maize and Potato in Abay Basin             y Eff       W    ...
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Soil fertility effect on water productivity of maize and potato in Abay Basin

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Poster prepared by Teklu Erkossa and S.B. Awulachew for the International Congress on Water 2011 Integrated Water Resources Management in Tropical and Subtropical Drylands, Mekelle, Ethiopia, 19-26 September 2011.

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Soil fertility effect on water productivity of maize and potato in Abay Basin

  1. 1. FU BerlinSoil F Fertility Effect on Water Productivity of Maize and Potato in Abay Basin y Eff W y f y Teklu Erkossa and S B. Awulachew S. B International Water Management Institute Introduction: Ab b i (E hi i part of Bl Nil ) i characterized b a mixed crop‐ I t d ti Abay basin (Ethiopian f Blue Nile) is h i d by i d Water Balance:  SF levels affected water balance components, except  Water Balance: SF l l ff t d t b l t t livestock i f d farming system (Fi 1) A i lt l productivity i l li t k rainfed f i t (Fig. 1). Agricultural d ti it is low d due t hi h to: high runoff  and  infiltration.  Of the 1450 mm rainfall received during the runoff and infiltration Of  the  1450  mm  rainfall  received  during  the  growing  period,  60%  infiltrates  while  the  rest  is  lost  as  runoff.  Of  the  i i d 60% i fil hil h i l ff Of h temporal and spatial variation in climate sever land degradation lack of appropriate climate, degradation, infiltrated  water,  276,  311  and  304  mm  percolates  under  poor,  near  infiltrated water 276 311 and 304 mm percolates under poor near technologies, technologies poor infrastructure & limited extension services Although rainfall is adequate services. adequate, optimal and non‐limiting SF conditions, respectively. The balance is either  ti l d li iti SF diti ti l Th b l i ith water productivity remains low due to poor crop, soil and water management practices. Soil p y p p, g p used  as  transpiration  (T)  or  lost  as  evaporation  (E) Improving  SF  used as transpiration (T) or lost as evaporation (E).  Improving SF fertility is f tilit i a prime f t li iti crop water productivity i areas where rainfall i not i factor limiting t d ti it in h i f ll is t decreased  E and  i d d E  d increased  T (b d T  (beneficial  consumption)  (Fi 2) Th fi i l ti ) (Fig.  2).  The  limiting (Drechsel et al 2004) This study investigated the effect of soil fertility (SF) levels on al, 2004). reduction  in  E  is  due  to  better  canopy  cover  under  improved  fertility,  reduction in E is due to better canopy cover under improved fertility which  attained  its  maximum  in  August.  This  corroborates  Cooper  et  al.  hi h tt i d it i i A t Thi b t C t l water productivity of maize and potato grown in sequence sequence. (1987) who suggested that application of fertilizers enhance crops water (1987) who suggested that application of fertilizers enhance crops’ water  use efficiency. ffi i Max. soil evaporation Actual soil evaporation Max. crop transpiration Actual crop transpiration Methodology: The FAO AquaCrop model Version 140 3 (R (Raes et al., 2009 St d t et al., 2009) was used t t l 2009; Steduto t l d to 120 simulate the grain and biomass productivity of maize 100 A ou (m ) m unt mm as well as th water b l ll the t balance of th system. I i ti f the t Irrigation 80 requirement and water productivity of potato 60 planted f ll i maize was estimated assuming th l t d following i ti t d i the 40 excess water during the rainy season is harvested for 20 use as supplementary irrigation Climate soil and irrigation. Climate, 0 r r r er er er t t t ly ly ly ne ne ne be be be us us us Ju Ju Ju ob ob ob crop date obtained from the basin master plan and Ju Ju Ju m m m ug ug ug ct ct ct te te te A A A O O O ep ep ep S S S research centers located within the basin were input for model validation and simulation. The Reference Soil fertility Non- li iti N limiting Poor Near optimal N ti l Evapotranspiration was estimated using the ETo status: t t Calculator [Raes et al., 2009]. The Relative Root [ , ] Fig.  2. Effect of soil fertility status on Evaporation and Transpiration Fig 2 Effect of soil fertility status on Evaporation and Transpiration Mean Square Error (RRMSE) Equ 1 and Coefficient of Equ.1 Fig. Fig 1 :The major farming systems in Efficiency (E) Equ.2 were used to examine the Abbay Basin y ( ) q Water Harvesting: The runoff water can be harvested for use as robustness of the model model, supplementary i i i of second crops. P l irrigation f d Potato planted 10 d l d days after f maize is harvested in October gives 4 8 and 10 t ha‐1 (dry weight) tuber 4, ∑ (O )2 N 1/ 2 − E yield under poor, near optimal and non‐limiting SF respectively (T bl 2) i ld d i l d li i i SF, i l (Table 2). ⎛ 1 n ⎛ E −O ⎞ 2⎞ i i E = 1 − i=1 Assuming 65% irrigation efficiency growing potato under near optimal efficiency, RRMSE RRM E = ⎜ ∑⎜ ⎟ ⎟ Equ.1  and q 2 Equ.2 q ⎜ N i =1⎝ O ⎠ ⎟ N ⎛ _ ⎞ ⎝ ⎠ ∑ ⎜ O i− O ⎟ and well‐fertilized conditions requires about 696 and 739 mm i i ti d ll f tili d diti i b t d irrigation ⎝ i=1 ⎠ water , which is about 17 and 25% higher than the potentially harvestable water. C t Consequently, either l tl ith less l d area should b used or crops with land h ld be d ith Three soil fertility scenarios were considered: Three soil fertility scenarios were considered: less water requirement should be chosen. However, increasing irrigation 1. Poor‐ representing the traditional no fertilizer use p g efficiency t 80% can permit growing potato on th same area of l d as ffi i to it i t t the f land 2. 2 Near optimal‐ representing use recommended rates of N and P maize. 3. Non‐limiting‐ representing use of recommended rates of N and P + other macro and l g p g f d d f d h d micronutrients Table  2. Productivity and Water Requirement of Potato grown after Maize Table 2 Productivity and Water Requirement of Potato grown after Maize Productivity (ton ha-1) NIR (mm) ( ) GIR ( 65% IE) (at ) Soil fertility status (mm) Results: The RRMSE percentage was low (8.1%) and the model efficiency (E) was close to R l p g ( %) y( ) Dry biomass y Yield+ 1 indicating that the model is robust enough to predict maize productivity in the area 1, area. Poor 5.1 51 3.8 38 414 637 Near optimal 10.5 10 5 7.9 79 452 696 Non limiting N li iti 13.1 13 1 9.8 98 480 739 Simulated Productivity and Water Balance Simulated Productivity and Water Balance Productivity of maize:  Moisture availability was not limiting, but soil fertility was the  Productivity of maize: Moisture availability was not limiting, but soil fertility was the Conclusion: A C AquaCrop can reasonably predict th productivity of bl di t the d ti it f main  source  of  variation  in  productivity.  About  39%,  75%  and  100%  of  the  potentially  i f i ti i d ti it Ab t 39% 75% d 100% f th t ti ll maize grown in Abbay river basin Soil fertility and the use of high yielding basin. achievable biomass yield can be obtained under the poor, near optimal and non limiting soil  achievable biomass yield can be obtained under the poor near optimal and non‐limiting soil varieties can significantly i i ti i ifi tl increase water productivity of maize and potato t d ti it f i d t t fertility conditions, respectively while the grain yield ranges between 2.5 t ha‐1 and 9.2 t ha‐1 f tilit diti ti l hil th i i ld b t 25th 1 d92th grown in the area. The increased water productivity of maize is achieved under  poor and non‐limiting soil  fertility  conditions,  with  a  corresponding  increase  in  under poor  and  non limiting  soil fertility conditions, with a corresponding increase in mainly b reducing evaporation and i i l by d i ti d increasing t i transpiration. H i ti Harvesting ti biomass and grain water productivity (Table 1). Assuming only 50% of the 3.03 million ha of  biomass and grain ater prod cti it (Table 1) Ass ming onl 50% of the 3 03 million ha of the excess water during the main can allow the growing of a second crop Nitisols  in  maize based farming system in the basin is planted to hybrid maize, about 10 Nitisols in maize  based  farming  system  in  the  basin  is  planted  to  hybrid  maize,  about  10  with supplemental irrigation irrigation. million ton and 14 million ton grain can be obtained with near optimal and non‐limiting soil  million ton and 14 million ton grain can be obtained with near optimal and non limiting soil fertility  conditions.  That  is, only row planting of hybrid seeds and applying recommended fertility conditions. That is,  only  row  planting  of  hybrid  seeds  and  applying  recommended  Reference: rates of nitrogen and phosphorus as practiced by research centres can increase productivity  rates of nitrogen and phosphorus as practiced by research centres can increase productivity Drechsel, P., Giordano, M. and Gyiele, L. 2004. Valuing nutrition in soil and h l d d y l l g l d by t ee o d as co pa ed to t e cu e t by three fold as compared to the current. water: concepts and techniques with examples from IWMI studies in developing world. IWMI R d l i ld Research P h Paper 82 I82. International W i l Water Table 1. Water productivity of maize as affected by soil fertility status T bl 1 W d i i f i ff db il f ili Management Institute (IWMI) Colombo Sri Lanka (IWMI), Colombo, Cooper P J M G C P. J. M., Gregory. P J K i P. J., Keatinge, J D H and B J. D. H. d Brown S C 1987 S. C.1987. Yield (t ha-1) % Biomass in reference to Water productivity (kg m-3) Effects of fertilizer variety and location on barley production under fertilizer, Soil fertility rainfed conditions i northern S i Fi ld C i f d diti in th Syria. Field Crops R 16 67 84 Res. 16, 67–84 Biomass Grain well watered well fertilized Biomass Grain Raes, D., Steduto, P., Hsiao, Raes D Steduto P Hsiao Th and Fereres E 2009 AquaCrop—The FAO Fereres, E. 2009. AquaCrop The Poor 7.5 2.5 100 39 5.1 1.7 crop model f predicting yield response t water: II M i algorithms and d l for di ti i ld to t II. Main l ith d Near N optimal i l 14.3 14 3 6.4 64 100 75 5.3 53 2.4 24 soft ware description Agron J 101:438–447 description. Agron. J. 101:438 447 Steduto, P., Hsiao, T.C., Raes, D., Fereres, E., 2009. AquaCrop—the FAO  St d t P H i T C R D F E 2009 A C th FAO Non limiting 19.2 19 2 9.2 92 100 100 5.4 54 2.6 26 crop model to simulate yield response to water. I. Concepts. J. Agron. 101,  crop model to simulate yield response to water. I. Concepts. J. Agron. 101, 426–437 426 437 For F more i f information contact: ( ti t t (e-mail) il) Adress: d t.erskossa@cgiar.org http://www.iwmi.cgiar.org/africa/east_africa/ p g g _

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