Microclimatological characteristics and soil pH adaptability of herbaceous mimosa (Mimosa strigillosa Torr. and Gray) at Nacogdoches, Texas, a new reclamation species in the southern United States

Two studies were conducted on herbaceous mimosa (Mimosa strigillosa); a microclimate study and a pH adaptability study. In the microclimate study, soil microclimates between the mimosa and bare ground were observed during a 12 month period (June 1993-May 1994). The microclimatic variables measured in the study included solar radiation, reflected solar radiation, air temperature, soil temperature at 2 cm depth, surface soil temperature, soil heat flux. relative humidity, precipitation, pan evaporation, wind speed and evapotranspiration. A floating lysimeter was built to study the evapotranspiration of the herbaceous mimosa. At the mimosa plot, surface temperature is cooler, outgoing shortwave and longwave radiation are lower, net radiation is higher, and water loss is increased. Net radiation is higher in the summer, under clear skies. and at the mimosa plot. Total evapotranspiration (ET) for the mimosa plot during the study period (June to October 1993) was 241.5 mm while total evaporation for the bare ground during the same period was 162.6 mm. ET for herbaceous mimosa can be empirically estimated using incoming solar radiation, daily mean air temperature and daily mean relative humidity with R;In the pH study, herbaceous mimosa seeds were planted in 40 pots which consisted of 10 different soil-pH scale treatments with 4 replicates. The soil-pH ranged from 4.0 to 8.0 with an increment of roughly 0.5. After 15 days, seedling emergence was observed and recorded. The plants were grown for 22 weeks. Then, they were dismantled for analyses of biomass, certain growth and development characteristics, and plant and soil nutrient-contents. The seedling emergence of herbaceous mimosa occurred in 3-4 days after seeding no matter what the soil pH was from as low as 4.1 or as high as 8.0. However, the emergence rate was only about 50-70% for pH in the range 4.7 to 6.6. After emerging, the survival rate was greater than 93% except in soil with a pH of 4.1 which was less than 50%. The optimum growth of herbaceous mimosa was on soils with a pH range of 6.2 to 7.1. In this pH range, herbaceous mimosa exhibits higher total dry biomass weight and lower root shoot weight and length ratio. It is not suitable to grow herbaceous mimosa on soils with pH of 4.1 probably due to toxicities caused by Al...