Optimizing Dryland Crop Management to Regional Climate. Part II: U.S. Southern High Plains Grain Sorghum Production

Steven Mauget,Zhanguo Xin,Chad Hayes,Kritika Kothari,R Louis Baumhardt,Yves Emendack,Srinivasulu Ale,Gary Leiker

doi:10.3389/fsufs.2019.00119

Abstract

Sorghum’s heat and drought tolerance make it, together with upland cotton, one of two crops produced profitably under dryland conditions in the U.S. Southern High Plains (SHP). Here, a simulation-based method evaluates management options that increase median SHP dryland sorghum yields and estimates those practice’s yield risk effects. This method generates climate-representative distributions of grain yields via a crop model driven by weather inputs from 21 SHP weather stations during 2005-2016. Optimal management practices for current SHP climate conditions were sought by generating yield distributions under 32 management options defined by 4 planting dates, 4 plant densities, and applied or no applied N. The highest median grain yields resulted from management options with the latest planting date (July 5) and the lowest plant density (24.7 K plants ha-1), while applied N had essentially no yield effect. Increased yields with later planting dates are consistent with sorghum’s growth cycle and SHP summer rainfall climatology. Confirming the low plant density yield effect may require additional field studies, as supporting evidence of higher yields at lower densities from other SHP field and modelling studies is inconclusive. These crop simulations, however, suggest late June to early July planting as part of management practices that maximize yields in dryland SHP sorghum production.

Highlights

Over the U.S Southern High Plains (SHP) sorghum [Sorghum bicolor (L.) Moensch] plays an important part in un-irrigated “dryland” agricultural production
This 96 kg ha−1 level is consistent with estimates of average SHP N levels (Bronson et al, 2009), it is high relative to the needs of sorghum for realistic dryland grain yields in the region
An additional 66 kg ha−1 N application had minor effects on grain yields, which, given the input costs of applied N, would likely lead to reduced profits. Under production conditions this highlights the need for soil N testing before planting, as residual SHP soil N levels may be high enough to support dryland sorghum production

Summary

Introduction

Over the U.S Southern High Plains (SHP) sorghum [Sorghum bicolor (L.) Moensch] plays an important part in un-irrigated “dryland” agricultural production. During 2016–2018 Texas was the second-ranked U.S state behind Kansas in planted sorghum acres [NASS S. Department of Agriculture National Agricultural Statistics Service), 2019], with a major production area located in the Texas Panhandle-SHP region. Sorghum’s heat and drought tolerance make it well-suited to the area’s semi-arid summer growing conditions, and its genetic diversity makes the crop potentially useful as forage, a gluten-free grain source, and in biofuel production (Dahlberg et al, 2011).

Methods

Results

Conclusion