Pearl millet (Pennisitum glaucum L.) is a warm season C₄ grass well adapted to semiarid climates where concerns over scarce and depleting water resources continually prompt the search for water efficient crop management to improve water use efficiency (WUE). A two-year study was conducted in the Southern Great Plains, USA, semi-arid region, to determine optimum levels of irrigation, row spacing, and tillage to maximize WUE and maintain forage production in pearl millet. Pearl millet was planted in a strip-split-plot factorial design at two row widths, 76 and 19 cm, in tilled and no-till soil under three irrigation levels (high, moderate, and limited). The results were consistent between production years. Both WUE and forage yield were impacted by tillage; however, irrigation level had the greatest effect on forage production. Row spacing had no effect on either WUE or forage yield. The pearl millet water use-yield production function was y = 6.68 × x (mm) − 837 kg ha⁻¹; however, a low coefficient of determination (r² = 0.31) suggests that factors other than water use (WU), such as a low leaf area index (LAI), had greater influence on dry matter (DM) production. Highest WUE (6.13 Mg ha⁻¹ mm⁻¹) was achieved in tilled soil due to greater LAI and DM production than in no-till.

As water levels in the Ogallala Aquifer continue to decline in the Texas High Plains, alternative forage crops that utilize less water must be identified to meet the forage demand of the livestock industry in this region. A two-year (2016 and 2017) study was conducted at West Texas A&M University Nance Ranch near Canyon, TX to evaluate the forage production and quality of brown midrib (BMR) sorghum-sudangrass (SS) (Sorghum bicolor (L.) Moench ssp. Drummondii) and BMR pearl millet (PM) (Pennisetum glaucum (L.) Leeke)) harvested under three regimes (three 30-d, two 45-d, and one 90-d harvests). Sorghum-sudangrass consistently out yielded PM in total DM production in both tested years (yield range 3.96 to 6.28 Mg DM ha⁻¹ vs. 5.38 to 11.19 Mg DM ha⁻¹ in 2016 and 6.00 to 9.87 Mg DM ha⁻¹ vs. 6.53 to 15.51 Mg DM ha⁻¹ in 2017). Water use efficiency was higher in PM compared to SS. The 90-d harvesting regime maximized the water use efficiency and DM production compared to other regimes in both crops; however, some forage quality may be sacrificed. In general, the higher forage quality was achieved in shorter interval harvesting regimes (frequent cuttings). The selection of suitable forage crop and harvesting regime based on this research can be extremely beneficial to the producers of Texas High Plains to meet their individual forage needs and demand.

Forage sorghum (Sorghum bicolor (L.) Moench) is well established in the Texas High Plains as a drought-tolerant forage that often requires additional feed to provide adequate protein for livestock. Intercropping sunnhemp (Crotalaria juncea L.), a legume, with forage sorghum, may increase crude protein. However, the optimal intercrop seeding ratio of sunnhemp to sorghum to improve crude protein content and maintain sufficient biomass is unknown. A two-year field experiment was conducted near Canyon, TX, USA, in 2020 and 2021 using sunnhemp intercropped at three seeding rates (16.8, 33.6, and 50.4 kg ha⁻¹) with forage sorghum at four seeding rates (0, 2.8, 5.6, and 11.2 kg ha⁻¹) under drip irrigation. This study was conducted to (1) evaluate growth potential for sunnhemp in a semiarid environment, (2) find a seeding ratio that can maintain forage sorghum dry matter production and improve forage quality, and (3) determine if a midseason harvest can be supported and further improve quality of the forage produced. Midseason, full-season, regrowth biomass, and forage quality were evaluated. Results indicated that a sunnhemp–forage-sorghum intercrop produced dry matter comparable to forage sorghum when sufficient heat units were obtained in the growing season. Forage with higher nutritive value was produced when the intercrop was harvested twice.

Despite declining water availability in semi-arid environments, demand for high-quality forages by the livestock and dairy industries continues to grow. Researching alternative crops for high quality forage and water use efficiency remains a priority for these regions to meet this growing demand. Cereal grass-legume intercropping system may provide such a viable alternative to traditional sole cropping to improve nutritive value, while maintaining the current yield levels with limited supply of water. A study was conducted near West Texas A&M University, Canyon, TX, USA. during 2020 and 2021 to evaluate forage sorghum [Sorghum bicolor (L.) Moench]-cowpea [Vigna unguiculata (L.) Walp] and pearl millet [Pennisetum glaucum (L.) Leeke]-cowpea intercrops for forage production, nutritive value (crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and in vitro dry matter digestibility (IVTDMD)), and water use efficiency (WUE) under limited irrigation. Treatments were sole pearl millet (PM), sole forage sorghum (FS), sole cowpea (C), or mixtures of either pearl millet-cowpea or forage sorghum-cowpea planted in the same row (PM-C or FS-C), alternating rows (millet-cowpea 1:1 (PM-C 1:1) or forage sorghum-cowpea 1:1 (FS-C 1:1), or two rows alternating (millet-cowpea 2:2 (PM-C 2:2) or sorghum-cowpea 2:2 (FS-C 2:2). Results from both study years indicated that FS-C 1:1 intercrop showed either greater or equal forage dry matter (DM) yield compared to sole FS or sole PM (14.5 Mg ha⁻¹ (FS-C 1:1) vs. 13.8 Mg ha⁻¹ (FS) vs. 11.9 Mg ha⁻¹ (PM)). Similarly, the relative advantage of FS-C 1:1 intercrop in improving WUE was also observed in the study compared to sole FS and sole PM (44 kg ha⁻¹ mm⁻¹ (FS-C 1:1) vs. 41.6 kg ha⁻¹ mm⁻¹ (FS) vs. 35.9 kg ha⁻¹ mm⁻¹ (PM). CP yield per hectare (estimate based on DM yield and percent CP content) was also greater for the forage sorghum-cowpea planted in 1:1 alternate rows. This suggests that producers in the semi-arid USA, especially in the Southern High Plains, can be significantly benefited from the utilization of cereal grass-legume intercropping production systems in lieu of sole cropping as the basis for livestock rations without compromising yield and water productivity.