Effect of Fertilizer, Sowing Date, and Seeding Rate on Biomass and Yield of Pea (Pisum savitum L.) Grown Under Dry Steppe and Steppe Conditions

The impact of different agronomic practices on pea adaptability to terminal drought conditions can provide increased knowledge on optimizing pea yield, biomass, and environmental footprints. Two field experiments in the layout of the split–split plot and a 3-factor (fertilizer × sowing date × seeding rate) design were carried out on pea crops in 2021 and 2022 in Kazakhstan’s dry steppe and steppe zones. The objective was to evaluate the significance of these factors and their interactions on biomass and yield based on 12 treatments in the dry steppe and 18 treatments in the steppe. In both zones, fertilizer effect on biomass and yield was significant (p < 0.05) and resulted in a biomass increase of 17% and a yield increase of 16% in the dry steppe and 19% and 17.9%, respectively, in the steppe. The sowing date’s effect on biomass and yield in both zones was also significant, with maximum yield with late sowing (20 May) and biomass increased by 10% compared to the earliest sowing date (10 May) and yield increase of 9.2% in the dry steppe, and 15.7%, and 30%, respectively, in the steppe. Seeding rate and none of the first- and second-order interactions between these three factors on biomass and yield were significant in either zone. The relationship between factors and final biomass and yield showed that fertilizer application was dominant. Our research also showed that yield was highly correlated (r = 0.8–1.0, p < 0.05) with biometric indicators of plants, such as the weight of seeds per 1 m2 and the weight of seeds per plant. The findings from this study indicate that adaptive crop production to increase the yield of peas can be used for environmental conditions of dry steppe and steppe based on the development of new agronomic practices, especially those that include fertilizer application with a combination of sowing dates.