Effect of irrigation on the yield of alfalfa for hay in Valle Central of Catamarca, Argentina

In the province of Catamarca there is a large area planted with alfalfa. Lack of knowledge of crop water requirements in this area constitutes a serious problem. An irrigation experiment was conducted in randomized blocks in Valle Central with four treatments and four replications. The treatments consisted in replenishing soil moisture content at different thresholds: 75, 50, 25 and 0% of the total soil water storage capacity. Dry-matter production per treatment was evaluated in seven cuttings. Results showed that when irrigating with a 75 and a 50% threshold, similar dry-matter yields were obtained equivalent to 25,674.4 kg ms.ha(-1) and 24,215.4 kg ms.ha(-1), respectively. Significant differences were found (p < 0.0001) between the means of these treatments and the other two treatments. An irrigation threshold of 25% yielded less than 16,366.7 kg.ha(-1) and an irrigation threshold of 0% yielded less than 9,970.9 kg.ha(-1). It can be concluded that alfalfa production is significantly reduced when irrigation intervals are very long.