Effects of Alternate Wetting and Drying Irrigation Regime and Nitrogen Fertilizer on Yield and Nitrogen Use Efficiency of Irrigated Rice in the Sahel

Koffi Djaman,Koichi Futakuchi,Kazuki Saito,Raafat El-Namaky,Suat Irmak,Valere Mel,Abdoulaye Sow,Baboucarr Manneh,Lamine Diop

doi:10.3390/w10060711

Abstract

The objectives of this study were to investigate water saving strategies in the paddy field and to evaluate the performance of some of the newly released rice varieties. Field experiments were conducted at Fanaye in the Senegal River Valley during two rice growing seasons in 2015. Three irrigation regimes ((i) continuous flooding, (ii) trigging irrigation at soil matric potential (SMP) of 30 kPa, (iii) trigging irrigation at SMP of 60 kPa) were tested in an irrigated lowland rice field. Irrigation regimes (ii) and (iii) are alternate wetting and drying (AWD) cycles. Four inbred rice varieties (NERICA S-21, NERICA S-44, Sahel 210 and Sahel 222) and one hybrid rice (Hybrid AR032H) were evaluated under five nitrogen fertilizer rates (0, 50, 100, 150 and 200 kg N ha−1). The results showed that rice yield varied from 0.9 to 12 t ha−1. The maximum yield of 12 t ha−1 was achieved by NERICA S-21 under AWD 30 kPa at 150 kg N ha−1. The AWD irrigation management at 30 kPa resulted in increasing rice yield, rice water use and nitrogen use efficiency and reducing the irrigation applications by 27.3% in comparison with continuous flooding. AWD30 kPa could be adopted as a water saving technology for water productivity under paddy production in the Senegal River Middle Valley. Additional research should be conducted in the upper Valley, where soils are sandier and water is less available, for the sustainability and the adoption of the irrigation water saving practices across the entire Senegal River Valley.

Highlights

Irrigation water is becoming increasingly scarce, in Sahel environments similar to the Senegal River Valley, where long-term average annual precipitation is less than 300 mm [1] and where rice production remains one of the main agricultural activities under double crop production practices [2]
During the hot and dry season (HDS), rice genotype Sahel 210 had the highest yield of 11.10 t ha−1, 11.10 t ha−1, while NERICA S-44 showed the lowest yield at almost all applied N rates under continuous flooding paddy (CF)
Irrigation water saving strategies in rice production are becoming increasingly important to Irrigation water saving strategies in rice production are becoming increasingly important to identify effective and sustainable crop production and management practices

Summary

Introduction

Irrigation water is becoming increasingly scarce, in Sahel environments similar to the Senegal River Valley, where long-term average annual precipitation is less than 300 mm [1] and where rice production remains one of the main agricultural activities under double crop production practices [2]. Rice potential yields as high as 12 t ha−1 under effective irrigation management can be achieved in this soil and climate with good crop and resources management conditions [3,4,5]. Actual paddy yield in the valley is about 6–6.5 t ha−1 on the Senegal side [6,7] and within the range of. It has been reported that rice yield decreases with the default of good agricultural management practices and inappropriate irrigation management [6,11,12], resulting in an increase of soil salinity in the Senegal River Delta areas [13]. Irrigation requirements are a major contributor to rice production cost because the cost of pumping water is high, accounting for about 28% of operating cost [9]

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