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African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730 EISSN: 2072-6589
Vol. 8, Num. 3, 2000, pp. 243-249
African Crop Science Journal, Vol. 8. No. 3, pp. 243-249

African Crop Science Journal, Vol. 8. No. 3, pp. 243-249

AN APPRAISAL OF IRRIGATED TEMPERATE AND TROPICAL MILLET VARIETIES IN THE SEMIARID REGION OF SENEGAL

Saliou Diangar, Tanou Ba and C. F. Yamoah1
Institut Senegalais de Recherches Agricoles, ISRA CNRA, Bambey, BP 53 Senegal
1Soil Institute, Kumasi, Ghana

(Received 6 November, 1998; accepted 2 May, 2000)

Code Number: CS00026

INTRODUCTION

Pearl millet (Pennisetum glaucum (L). R. Br.) is the main staple in the diet of people in northern Senegal. Yields are generally low because it is entirely rainfed and rainfall in this region is presently low (<300 mm/year) and fluctuates from month to month and even within months (Dancette, 1974; INTSORMIL, 1993). Limited rainfall in northern Senegal is partly attributed to advancing desertification of the Sahelo-Sudanian region. Furthermore, soils of the semiarid region are sandy, infertile and contain low levels of organic matter. Lack of improved varieties as well as poor crop and soil management also contribute to the low productivity under peasant conditions in this environment.

Researchers in Senegal, Niger and other semiarid countries have found that increased productivity of millet is possible with judicious management under favourable climatic conditions (Bationo et al., 1993). Management decisions under farmers’ control include moderate application of manure and compost, a mixture of low doses of inorganic fertilisers with manure or compost, rotation with legumes, varietal choices, appropriate land preparation techniques and proper sowing dates.

Farmers do not have any direct control on rainfall but indirectly they manipulate it through moisture retention strategies such as local irrigation canals, mulching and ditches. Added to that, in a move to intensify land use and boost cereal production in the light of growing human and livestock populations, the government has provided irrigation facilities on 240,000 ha in northern Senegal. Since millet has much lower water requirement than flooded rice, a much larger area of land could be cultivated with millet. This could be a more efficient way to use scarce irrigation water and provide significantly greater food production than flooded rice and utilise irrigation scheme resources at periods unfavourable for other crops. A millet hybrid from Nebraska (USA) and an early local improved variety were tested under various cultural practices. The objective of the study was to determine the response of improved millet varieties to crop management (fertilisation, plant population and land preparation) under irrigation.

MATERIALS AND METHODS

The study was conducted in 1991 and 1992 with double cropping each year (i.e., four test periods) at the Thiago and Fanaye villages located in Senegal River Valley in north Senegal. The two villages belong to the Sahelo-Sudanian agroecological zone of Senegal (Bèye, 1977). The soils are Alfisols (USDA, 1975) and generally deficient in major nutrients (Nicou, 1976; Ndiaye, 1989; Piéri, 1989). Rainfall is low (250 to 300 mm) and uncertain; followed by a long dry season usually lasting about 8 months. Mean annual temperature is 20°C to 35°C. Additional information on the Sahelo-Sudanian agro-ecological zone of Senegal is provided by Sagna (1976).

Six field trials under irrigation were conducted, four in 1991 with two planted on 13 of February at Thiago (experiments 1 and 2) and two on 21 of August at Fanaye (experiments 3 and 4), and two in 1992,both planted on 11 of February (experiments 5 and 6). The design of the first trial in 1991 was a split plot with four replications. The main plots were millet genotypes, early dwarf hybrid 68 A x MLS from University of Nebraska, Lincoln, Nebraska, USA and a local dwarf synthetic variety, GAM 8201. Subplots were either three land preparation techniques or fertiliser at three levels. The genotype differences were important and were deliberately chosen, 68A x MLS and GAM 8201 were both dwarf and likely to respond to higher plant densities; GB87-35 is medium tall. All are shorter season, reaching physiological maturity in about 80 days, 10-15 days earlier than indigenous Senegalese varieties. Land preparation techniques were: 1) flat; 2) single ridges (width = 30 cm and height = 40 cm); and 3) double ridges (width = 100 cm and height=30 cm). All land preparation treatments received 22 N, 21 P and 39 K kg ha-1 at planting and 67 N kg ha-1 urea as a top dressing 2 weeks after planting. The fertiliser subplot treatments applied in 1991 were: 1) 15 N, 14 P and 26 K kg ha-1; 2) 22 N, 21 P and 39 K kg ha-1 + 67 kg N ha-1 as urea; and 3) 30 N, 28 P and 52 K kg ha-1 + 90 kg N ha-1 as urea all applied at planting.

The third and fourth experiments in 1991 minor season were modified to include plant density as an additional treatment and the synthetic variety GAM 8201 was replaced with variety GB 87-35. Research protocols of the third and fourth experiments were split-split-plot with four replications. Main plots were three fertiliser levels: 1)15 N, 14 P and 26 K kg ha-1 + 45 N kg ha-1 as urea (divided into equal halves for top dressing at first weeding and 30 days later), 2) 22 N, 21 P and 39 K kg ha-1 at planting and 67 N kg ha-1 as urea (divided into equal halves for top dressing at first weeding and 30 days later) and 3) 30 N, 28 P and 52 K kg ha-1 + 90 kg N ha-1 as urea (divided into equal halves for top dressing at first weeding and 30 days later). Subplots were land preparation on flat, simple ridges and double ridges. Sub-sub plots for variety GB 87-35 were plants spaced 80 x 80 cm, 80 x 60 cm, and 80 x 40 cm and sub-subplot size was 11.52 m2. Spacings for variety 68A x MLS were 70 x 30 cm; 70 x 20 cm; 60 x 30 cm, and 60 x 20 cm.

The rest of the studies conducted in 1992 examined the use of reduced levels of fertilisers on hybrid 68 A x MLS and frequency and quantity of water applied through irrigation. Fertiliser treatments were controlled with no fertiliser, 5 N, 4 P and 8 K kg ha-1, 5 N, 4 P and 8 K kg ha-1 + 22 N kg ha-1 as urea, and 10 N, 9 P and 19 K kg ha-1 + 45 N kg ha-1 urea. Experimental design was a randomised block design with four replications. The weekly or twice weekly irrigation treatments consisted of a total of 693 mm water (maximum seasonal amount of water used by millet) or 526 mm water (75% of the maximum consumption). The design was a 2 by 2 factorial in a randomised complete block with four replications. Maximum water consumption (Mc) was calculated as: Mc = Kc * Ev, where Kc = crop coefficient and Ev = evapotranspiration. Statistical analyses were performed using SPSS (Norusis, 1997) and MSTAT-C (MSU, 1988).

RESULTS AND DISCUSSIONS

Land preparation did not significantly (P>0.05) affect average yields of the Nebraska (68 A x MLS) and the local synthetic (GAM 8201) varieties (Table 1). However, mean yields of the local synthetic variety planted on the flat increased by about 58% and 26%, relative to planting on single and double ridges, respectively. This finding is noteworthy, because flat planting is cheaper than ridge planting. Conversely, the Nebraska variety performed better in single ridges, showing a 14% increase over the flat. Average yields of both millet genotypes, the Nebraska (4025 kg ha-1) and the local synthetic (4018 kg ha-1) were not significantly different (P>0.05) under irrigation, but yields of the two varieties were much higher than yields on farmers’ fields under rainfed conditions (430 - 1230 kg ha-1) in the semiarid environment (Bationo et al., 1993).

The main effect of fertiliser was not significant (P>0.05) nor was average varietal difference (Table 1), even though the yield of the local synthetic outperformed the Nebraska hybrid by 15 %. However, doubling the fertiliser rate of 15 N, 14 P and 26 K kg ha-1 + 45 N kg ha-1 urea, resulted in a significant (P<0.05) 20% yield increase of 3295 kg ha-1 to 3911 kg ha-1 for the Nebraska hybrid whereas the local synthetic variety had a 10% yield reduction. Apart from genetic differences of the two genotypes, reasons for the varietal differences are unclear; we suggest further research on this subject.

Results of yields for the new improved variety (GB 87-35) and the Nebraska hybrid (68 A x MLS) in separate experiments are given in Tables 2 and 3. Low yields in Tables 2 and 3 were principally due to infestation of stalk borers (Coniesta ignefusalis) and flower-sucking insects (Psalydollita fusca and Cylindrothorax dussaulti). These insect pests caused about 30 % yield reduction. Fertiliser affected yield of GB 87-35 (P<0.05) but methods of land preparation and plant density did not (P>0.05) (Table 2). The yield of 1525 kg ha-1 with 22 N, 21 P and 39 K kg ha-1 and 67 N kg ha-1 urea was not different from 1601 kg ha-1 with 30 N, 28 P and 52 K kg ha-1 + 90 N kg ha-1 as urea but both of these were significantly higher than yields from 15 N, 14 P and 26 K kg ha-1 + 45 N kg ha-1 as urea. Thus, from this the recommended fertiliser rate is 22 N, 21 P and 39 K kg ha-1 and 67 N kg ha-1 urea in combination with any of the planting arrangements and land preparation methods for variety GB 87-35.

The results shown in Table 3 indicate that fertiliser did not (P>0.05) affect yields of the Nebraska variety but land preparation techniques and cropping patterns did (P<0.05). Also, ridges, both single and double, improved yields of the Nebraska millet variety relative to planting on the flat, consistent with the other study mentioned above. Yields of closer spacings between rows (60 cm x 30 cm or 60 cm x 20 cm) were superior to wider (70 cm x 20 or 30 cm) spacings. It appears that the best cultural practices to attain optimum yields of the Nebraska hybrid are ridges (large or small) and a high plant population density. Average yields were higher with the Nebraska hybrid.

Results of the effect of reduced fertiliser rates on the Nebraska variety are presented in Table 4. Both grain and stover yields of millet responded to fertiliser (P<0.05). Highest yields for grain (4880 kg ha-1) and stover (6330 kg ha-1) were obtained with the application of 10 N, 9 P and 17 K kg ha-1 + 45 N kg ha-1 urea. The lowest yields came from 5 N, 4 P and 8 K kg ha-1. The 36% difference in yield between the control (3300 kg ha-1) and the 5 N, 4 P and 8 K kg ha-1 (2440 kg ha-1) plots is not significantly different (P>0.05).

Yields of the Nebraska hybrid in Table 1 compared favourably with the reduced yields in Table 4, thus, it may be safe to recommend less fertiliser (10 N, 9 P and 17 K kg ha-1 + 45 N kg ha-1 as urea) to make this technology affordable to many farmers. Recent and past experiences in the semiarid region of Senegal have demonstrated that a combination of mineral fertilisers and animal manure or compost improved rainfed millet and peanut yields better than either manure or fertiliser alone (Charreau and Nicou, 1971; Badiane, 1988). Additional research is needed on irrigated millet to determine whether adding organic amendments could further improve yield in the presence of inorganic fertiliser.

Data on yield and yield components of the Nebraska hybrid as affected by frequency and amount of irrigation water are given in Table 5. Neither the frequency nor the amount of water significantly (P>0.05) affected millet yield. However, plots irrigated with 75% maximum water needed by millet tended to yield more than plots with full water dose. Millet is a crop adapted to low moisture conditions, particularly unsaturated soils, thus having lower water requirements (Vachaud et al., 1978; Sarr et al., 1998). Also, irrigation once per week yielded slightly higher than twice per week (Table 5). Governments and private organisations of the sub region should consider developing low level irrigation facilities to promote higher and more stable yields of millet and other cereal crops. These crops may offer a more efficient way to use scarce irrigation water to produce more food per unit area than high water-requiring crops such as lowland rice. However, environmental impact assessment studies should be done before implementing such programmes.

ACKNOWLEDGMENTS

This project is a contribution of Natural Resource Based Agricultural Research project and was supported by a grant from USAID/CID/Senegal project #685-0285-C-00-2329-00. Appreciation is expressed to Dr. David Andrews of University of Nebraska-Lincoln, for supplying 68 A X MLS and his advice on the design of the studies and Dr. Richard P. Dick, Oregon State University, for editing the manuscript.

REFERENCES

  1. Badiane, A.N., 1988. Courbe de réponse à des doses croissantes de fumier (Thilmakha). Essai travail du sol (Sole III Nord du CNRA de Bambey). Essai régénération des sols Ndiémane. Résultats de 1987. ISRA-CNRA de Bambey.
  2. Bationo, A., Christianson, C.B. and Klaij, M.C. 1993. The effect of crop residues and fertilizer on use of pearl millet yields in Niger. Fertilizer Research 34:251-258.
  3. Bèye, G. 1977. Dégradation des sols au Sénégal. Situation actuelle et perspectives. ISRA-CNRA. 23pp.
  4. Charreau, C. et Nicou, C. 1971. L’amélioration du profil cultural dans les sols sableux et sablo argileux de la zone tropicale sèche Ouest-Africaine et ses incidences agronomiques. Agronomy Tropicale 26:1183-1247.
  5. Dancette, C. 1974. Les besions en eau des plantes des grandes culture au Senegal. In: Isotopes and radiation techniques in soil physics and irrigation studies. Vienne, AIEA. pp. 351-371.
  6. INTSORMIL. 1993. Annual report 1992. Senegal Country Report. University of Nebraska-Lincoln, NE. pp. 277-230.
  7. MSU. 1988. Microcomputer Statistical Program. Michigan State University, East Lansing, MI.
  8. Ndiaye, J.P. et Sagna, A. 1989. La fertilisation des cultures au Sénégal. Bilan diagnostic et perspectives. Ministère du Développement Rural. 99pp.
  9. Norusis, M. J. 1997. SPSS 7.5. Guide to data analysis. Prentice Hall, Upper Saddle River, NJ.
  10. Piéri, C. 1989. Fertilité des terres des savanes. Bilans de 30 ans de recherche et de développement agricole au Sud du Sahara. Min. Coopération et CIRAD-IRAT. 444 pp.
  11. Sagna, A. 1976. Le bilan de pluies au Senegal de 1944 a 1973. Dakar, Faculte des Lettres et des Sciences Humaines, Dept. de Geographie, 267 pp.
  12. Sarr, B., Boggio, D., Annerose, D. and Macauley, R.H. 1998. In: Approach in modeling environmental factors and genotypes interaction: a case study of millet (Pennisetum Glaucum). European Society of Agronomy, 5th ESA Congress, Nitra, Rep. Slovaque, 28 Juin - 3 Juillet 1998.
  13. USDA. 1975. Soil taxonomy. A basic of soil classification for making and interpreting soil surveys. U.S. Soil Conservation Service.
  14. Vachaud, G., Dancette, C., Sonko, S. et Thony, J.L. 1978. Méthodes de caractérisation hydrodynamique in situ d’un sol non saturé du Sénégal en vue de la détermination des termes du bilan hydrique. Ann. Agron. 29:1-36.
TABLE 1. Effects of land preparation and fertiliser on grain yields of irrigated millet varieties in the semiarid area of Senegal (Experiments 1 and 2)
Variety Land preparation Yield (kg ha-1) Fertiliser Yield (kg ha-1)
68A x MLS Flat 3,700 60 N, 14 P and 26 K kg ha-1 3,300
Simple ridge 4,230 90 N, 21 P and 39 K kg ha-1 3,680
Double ridge 4,145 120 N, 28 P and 52 K kg ha-1 3,920
GAM 8201 Flat 4,974 60 N, 14 P and 26 K kg ha-1 4,390
Simple ridge 3,146 90 N, 21 P and 39 K kg ha-1 4,060  
Double ridge 3,930 120 N, 28 P and 52 K kg ha-1 3,903
    Level of significance   Level of significance
Variety (V)   ns Variety 0.079
Land preparation (LP)   ns Fertiliser ns
V x LP   0.043 Variety x fertiliser ns
TABLE 2. Effect of fertiliser, land preparation and plant density on grain yields of irrigated millet (variety GB 87-35) in the semiarid area of Senegal (Experiment 3)
Fertiliser Density Flat Simple ridge Large ridge
Yield (kg ha-1)
60 N, 14 P and 26 K kg ha-1 80 cm x 80 cm 1,120 1,170 1,330
80 cm x 60 cm 1,290 1,040 1,590
80 cm x 40 cm 1,170 1,250 1,490
90 N, 21 P and 39 K kg ha-1 80 cm x 80 cm 1,950 1,410 1,700
80 cm x 60 cm 1,490 1,270 1,610
80 cm x 40 cm 1,300 1,660 1,350
120 N, 28 P and 52 K kg ha-1 80 cm x 80 cm 1,770 1,510 1,800
80 cm x 60 cm 1,640 1,460 1,610
80 cm x 40 cm 1,630 1,610 1,370
Level of significance
Density (D) ns      
Fertiliser (F) 0.013      
Land preparation (LP) ns      
LP x F ns      
LP x D 0.047      
LP x D x F ns      
TABLE 3. Effect of fertiliser, land preparation and plant density on grain yields of irrigated millet (hybrid 68 A x MLS) in the semiarid area of Senegal (Experiment 4)
Fertiliser Density Flat Simple ridge Large ridge
kg ha-1
60 N, 14 P and 26 K kg ha-1 70 cm x 30 cm 2,030 2,340 2,030
70 cm x 20 cm 2,170 1,790 2,380
60 cm x 30 cm 2,060 2,680 2,420
60 cm x 20 cm 2,730 2,630 2,330
90 N, 21 P and 39 K kg ha-1 70 cm x 30 cm 1,850 2,250 2,200
70 cm x 20 cm 1,680 2,170 2,420
60 cm x 30 cm 2,370 2,730 2,830
60 cm x 20 cm 1,890 2,530 2,280
120 N, 28 P and 52 K kg ha-1 70 cm x 30 cm 1,280 2,650 2,820
70 cm x 20 cm 1,790 2,420 2,680
60 cm x 30 cm 2,370 2,680 2,980
60 cm x 20 cm 1,740 2,630 3,130
Level of significance
Plant density (D) 0.0001      
Fertiliser (F) ns      
Land preparation (LP) 0.004      
LP x F 0.094      
LP x D ns      
LP x D x F ns      
TABLE 4. Effects of reduced rates of mineral fertiliser on grain and stover yields of irrigated millet (hybrid 68 A x MLS) in the semiarid zone of Senegal in 1992 (Experiment 5)
Fertiliser Grain yield (kg ha-1) Stover yield (kg ha-1)
Control (without fertiliser) 3,300 4,090
5 N, 4 P and 8 K kg ha-1 2,440 3,020
27 N, 4 P and 8 K kg ha-1 3,810 4,740
55 N, 9 P and 25 K kg ha-1 4,880 6,330
Level of significance
Fertiliser 0.062 0.004
TABLE 5. Millet (hybrid 68 A x MLS) grain yield and yield components as affected by irrigation frequency and amount of water in 1992 (Experiment 6)
Frequency Amount Yield Stover Non productive tillers (no. of tillers ha-1) Productive tillers Head g/m2
kg ha-1
1/week Maximum 3,820 5,423 172,590 637,135 3,155
75% maximum 4,680 6,915 274,210 727,465 3,841
2/week Maximum 3,580 5,202 220,980 582,290 2,974
75% maximum 4,390 6,472 196,786 640,361 3,644
Level of significance
Frequency (F)   ns ns 0.17 0.13 ns
Amount (A)   0.12 0.02 ns 0.12 0.13
F x A   ns 0.05 ns ns ns
About 75 % of 693 mm water per year
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