Simulating maize emergence using soil and climate data

Experimental programs aimed at improving seedling establishment in the semiarid tropics require quantitative information concerning the interaction between the seedbed environment and preemergent seedling growth, The model here described links a soil heat and water model, a soil strength model, and a temperature-dependent maize (Zea mays L.) shoot growth model to predict the response of preemergent maize seedlings to a physical environment typical of the semiarid tropics. In comparisons with field measurements taken in the semiarid tropics under high drying rate conditions, the model simulations yielded accurate representations of soil water, temperature, strength, and preemergent shoot growth of maize, The model was also used to compare the effects of radiation- vs, wind-dominated evaporative demand on preemergent seedling growth in a hardsetting seedbed. Results showed that under radiation-dominated conditions, the early onset of high soil temperature limited seedling growth, while under wind-dominated conditions, the early development of high soil strength affected seedling growth first. Simulations using surface mulch as an ameliorative management practice showed that mulch greatly reduced soil evaporation, thereby eliminating high soil strength as a limitation to seedling establishment, Results indicate that the model is a potentially useful tool for investigating the likely effects of soil and climate on seedling emergence.