Karnes Neill

Yield response of pea, lentil and chickpea to phosphorus addition in a clay loam soil of central Montana

Production of pea, lentil and chickpea, as a forage and food source, has increasingly become a popular agricultural practice in the northern Great Plains. While many local soils are rich in phosphorus (P), it has been commonly believed that P-fertilization still has potential to promote production. A two-year (2003–2004) field study was conducted to fine-tune P fertilization strategies in a clay loam soil (14 mg Olsen-P kg−1, sodium bicarbonate extractable soil P) of central Montana. Treatments included three varieties for each of the three crop species (pea: Majorest, Mozart and Delta; lentil: Vantage, Richlea and Brewer; and chickpea: Yuma, Myles and Chico), a control (0 P) and three P rates (7.3, 14.7 and 22.0 kg P ha−1) in triple super-phosphate (TSP), arranged in a randomized complete block design with four replicates. Responses of grain and forage yield to P addition varied depending on crop species and varieties within each species. Grain yields correlated quadratically to the rate of P applied for Majoret, Mozart and Brewer. Forage yield of Majoret, Mozart, Vantage and Richlea was significantly increased with P addition. P-addition enhanced vegetative growth as evidenced by the increased shoot-grain ratio. Chickpea varieties did not respond to P fertilization. The best yielding variety in this soil was Mozart, Vantage and Myles from each species, respectively. To facilitate decision making for producers, the relationship between the increased yield and the rate of P application was quantified. Averaged over two years, by growing Majoret, Mozart, Vantage and Richlea for forage at low rate of P application (7.3 kg P ha−1), income was about 1.8–2.3 times of the cost of P fertilizer applied.