Sudan - Gezira study mission (Vol. 5 of 15) : Annex II : appendix 2 : irrigation and agronomy

# rc9 6 5th e- C. RETURN TO RECORDS CENTER ROOM HB-1 1966-68 MATERIAL loX NO. 0) Hm Z>~~~~~ Je C 0 X. co zl 0~~R E  ANNEX II APPENDIX 2 - IRRIGATION AND AGRONOMY TABLE OF CONTENIS CHAPTER PAGE 1. IRRIGATION AND AGRONOMYR... .................... 1 2. IRRIGATION IN THE GEZIRA. ..................... 2 Climatemperatur.. .0.. .... 2 RaThflill............................. 2 Temperature........00*00. 2 The'Blue Nieo. 5 Sudan's share of Nile Watersr........ 5 Roseires water... te.r..0......... 6 Uncertainty of flow.........o....... 7 Withdrawal of water at Sennar....... 9 Brief Description of the Gezira Night Storage Irrigation System...s............ 13 The irrigation network.............. 13 Capacity of the network: .......... 13 : night storage 15 : operation 16 Field layout: ......V660... 16 : field channels 17 : operation 17 Basin irrigation: 17 : watering technique 18 : making the messir 18 Miscellaneous. . .... ......... . .. 18 Estimation of Irrigation Requirements .19 Water requirements...ur... e .s... . .... 19 Rainfall contribution to plant needs 19 Irrigation efficiency..... 20 Reliability of estimates....mates.. 20 Estimated and actual irrigation for the 1964/5 crop........... ... 20 Reducing the peak demand for irrigation, .....o...... -oo.ofooo. 21 Estimates of Future Irrigation Demand 22  CHAPTER PAGE 3. AREAS ............................... o........ . .. 25 Base year for the mission's calculations ...... ........ ............... . 25 Recent expansion of the Scheme ...... 27 Future expansion of the Scheme ...... 28 4. COTTON YIELDS . . . .......................... * . 32 Data for analysis ................... 32 Geographical position ...... ....... 34 Rainfall and yield .................. 34 Rainfall distribution ............... 36 Yield differences between Blocks .... 37 5. ALTERNATIVE CROPS ........................... . 39 Substitution Crops ......................... 40 American Upland cotton: ............ 4O : field trials 40 Barbeton groundnuts................. 44 Combinable dura..................... 45 New Crops ................. 5 Perennial crops: sugar cane..e... 45 : tree cro ps .........6 Pastures and fo dders ................6 : fodders and grasses 7 : forage and pasture legumes . .......... 47 Annual crops : oil seeds .. .... 47 :rice ............... . ............. 48 : hard fibers ........ 49 6. ROTATIONS, HOLDINGS AND LAND USE ............. 50 Gezira Main Rotations .................... 50 Planagil Rotations ...................... . 51 Intensification and diversification 51 : Working Party proposals 52 The mission's proposals 53 Intensity of Cropping .55 Intensity and land use in the mission's proposals 55 H oldnsd.................. 56 The mission's proposals for identifiable,contiguous holdings 57 Crop areasr............... .. .. ..... 58  ANNEX II APPENDIX 2 C H A P T E R 1 IRRIGATION AND AGRONOMY Most of the mis6ion's conclusions on irrigation and agronomy have been described in Annex 2. The main purpose of this appendix is to set out in greater detail the calculations of irrigation needs and the analyses of yield trends and to discuss the introduction of new or substitute crops. A brief description of the Gezira Night Storage Irrigation System is included in Chapter 2 while the organization of the present tenancy system is described in Chapter 5.  ANNEX II APPENDIX 2 C H A P T E R 2 IRRIGATION IN THE GEZIRA CLIMATE Rainfall Annual rainfall for the possible irrigation areas lying within the vast tract between Roseires and Khartoum, and in which the Gezira Scheme lies about midway, varies from about 800 mm (approx. 32 inches) at the Roseires to about 160 mm (approx. 6 inches) at Khartoum in the north. More specifically, at the Gezira Agricultural Research Station near Wad Medani, approximately at the center of the Gezira, annual rainfall is of the order of 380 mm, distributed over the six months, May through October. At 50 percent probability, the range about the mean (based on 15 years of data) lies within the limits of 326 to 439 mm (13 to 17 inches); details by months are given in Table 1. It will be noted that the majority of the arnlual rainfall occurs in July through September; in August, the main planting month, the range is about 100 to 183 mm, or perhaps one-third of the annual rainfall. Variations in rainfall throughout the Scheme, and their effect on yield variations, are discussed in a later chapter. Temperature Temperature ranges are also important in planning cropping patterns. W4hether a beneficial effect on cotton boll development is due to large diurnal temperature differences, or whether a lower night temperature is more important, is perhaps an academic issue. What is important is that optimum growth takes place between October and December. 1/ Diurnal temperature ranges are greater, and indeed the minima are7appreciably lower, during this period. But after the end of December the low night temperatures are likely to limit growth. In view of the importance this concept will have on choice of sowing dates for crops, these data are given in Table 2. Average monthly 1/ Agriculture in the Sudan. Ed. J. D. Tothill, Oxford Univ. Press, 1952 (page 471).  ANNEX II - 3 - APPENDIX 2 minima for the five months, November through March, are less than 200C (680F) and the diurnal range is 170C (310F) or more for the eight months, October through May. Table 2 also shows that for the three months of the 'dead' season, April through June, average monthly maxima usually exceed 400C (1040F). Table 1: RAINFALL OVER 15 YEARS FOR WAD MEDANI (millimeters) Year May June July August September October Total 1950 5 24 150 101 84 43 407 1951 14 12 30 125 37 19 237 1952 19 40 75 173 65 9 381 1953 45 41 85 158 29 15 373 1954 16 7 158 162 107 10 460 1955 24 62 77 73 73 9 318 1956 2 36 121 160 104 18 441 1957 4 12 113 161 32 3 325 1958 26 40 212 115 42 Nil 435 1959 3 31 161 273 83 5 556 1960 1 29 143 34 48 15 270 1961 Nil 64 90 193 13 7 367 1962 3 70 137 149 33 36 428 1963 48 13 115 118 24 Nil 318 1964 Nil 19 138 182 30 52 421 Mean 14.0 33.3 120.3 145.1 53.6 16.1 382.5 (Equiv- alent Inches) (0.55) (1.31) (4.74) (5.71) (2.11) (0.63) (15.06 50 percent range in millimeters: Lower 3.3 18.8 84.2 99.5 31.8 5.5 326.3 Upper 22.7 45.4 150.6 182.8 71.0 24.7 438.6  AX'NEX II APPENDIX 2 Table 2 MONTHLY TEMiPERATURE DATA FOR THE GEZIRA REGION (