Interseeding alfalfa (Medicago sativa L.) can improve forage quality of grasslands by adding a high‐protein species, but this runs the risk of accelerating soil water depletion. The objective was to evaluate effects of cultivar and row spacing of alfalfa on soil water balance and plant water potentials (Ψ) of two upright‐type cultivars, NuMex Bill Melton and WL 440HQ, and a prostrate‐type Falcata‐Rhizoma blend, interseeded into native grasses in October 2015 near Lubbock, Texas. Alfalfa was interseeded at 36‐cm (narrow) and 71‐cm (wide) row spacings. Soil volumetric water content (VWC) and midday Ψstem and Ψleaf were measured weekly in 2017 and 2018 growing seasons. Soil VWC was not affected by alfalfa cultivars (P > .05), whereas alfalfa row spacings differed (P < .05). Narrow spacing caused lower (P < .05) VWC than wide spacing relative to the grass‐only control in both the upper 40‐ and 40‐ to 100‐cm layers of the soil. Wide‐row spacing had similar VWC to control in 2017 for both soil layers (P > .05). Soil water depletion increased with alfalfa crown density (r = .60, P < .05) in association with enhanced evapotranspiration and denser root mass below 30‐cm soil depth. Grass and alfalfa Ψstem and Ψleaf were depressed in narrow rows relative to wide rows and control, indicating that presence of alfalfa intensified competition with the grass for soil water. The wide‐row treatment seldom had adverse effects on grass water stress. Wide‐row spacing achieved a favorable compromise between enhanced water use and improved stand productivity.

Core Ideas A noncalibrated PR2 capacitance probe showed significant deviations from actual soil water content. Calibration improved the accuracy and precision of soil moisture monitoring with the PR2. Calibration was necessary for using the PR2 probe for research‐quality soil water measurements. Multi‐depth capacitance sensors are popular to monitor soil water content for scheduling irrigation thanks to their ease of operation and maintenance. The PR2/6 Profile Probe (Delta‐T Devices) measures soil moisture by using either the manufacturer's built‐in equation or a user‐calibrated equation if the soil is high in clay or organic matter. The objectives were to evaluate the performance of the PR2/6 Profile Probe in a perennial grassland and to develop a site‐specific equation to correct probe measurements in Pullman (fine, mixed, superactive, thermic Torrertic Paleustolls) clay loam soils. Permittivity recorded by the profile probe was regressed on the gravimetrically measured soil volumetric water content (VWC). Parameters were optimized to obtain least RMSEs. The default equation provided by the manufacturer estimated VWC with average RMSE and r2 values of 0.053 m3 m–3 and 0.71, respectively. New calibration coefficients were effective in explaining 91% of the variability in soil VWC measurements and reducing RMSE to 0.017 m3 m–3. The results indicate that site‐specific calibration of the capacitance probe is necessary to attain research‐quality accuracy and precision when applied to grasslands in Pullman clay loam and associated clay loam soils.

In Nepal, rice (Oryza sativa L.) is widely planted manually by transplanting 20 to 30-days-old seedlings into puddled soil. However, transplanting is becoming increasingly challenging due to unavailability and the high cost of labor and energy, restricted supply of irrigation water, and decline of soil quality (Chauhan, 2012b). Depending on the growing season, climatic conditions, soil types, and hydrological condition, the total seasonal water input for a puddled transplanted rice ranges from 660 to 5280 mm (Bouman and Tuong, 2001). As a result, DSR is gaining in popularity as it is an economical alternative to transplanted rice. Direct-seeding of rice on pulverized soil reduces total labor requirement by 11 to 66%, saves 19 to 24 person-d ha-1, resulting in earlier and easier crop establishment (Rashid et al., 2009). DSR has the potential to reduce water and labor use compared to transplanted rice by eliminating the puddling phase and avoiding continuous standing water (Kumar and Ladha, 2011). Direct seeding reduces irrigation requirements by 30% of the total irrigation water required for transplanted rice (1400 to1800 mm) (Gopal et al., 2010), and results in greater tolerance or rice to water deficit (Yadav et al., 2004). Also, DSR matures 8 to11 d earlier than transplanted rice, which facilitates the earlier establishment of the following winter wheat (Balasubramanian and Hill, 2000). Despite several advantages, weeds are considered a major biological constraint of DSR systems (Dhakal et al., 2015; Chauhan, 2012a), resulting in inferior yields and poor stand establishment compared to transplanted rice (Singh et al., 2005). More than 50 weed species reported to be a significant cause of yield loss in DSR (Gianessi et al., 2002). It was estimated that rice yields were reduced by 80% (Mahajan et al., 2009), and even up to 100% in DSR compared to transplanted rice when no weed management practices were implemented (Sharma et al., 1977). Weeds compete with rice for light, nutrients, and water, ultimately diminishing crop growth and development. Singh and Dash (1988) reported that an increase in dry weed biomass at the

Semiarid pasture management strategies can affect soil hydraulic and thermal properties that determine water fluxes and storage, and heat flow in unsaturated soils. We evaluated long-term (>10 years) perennial and annual semiarid pasture system effects on saturated hydraulic conductivity (ks), soil water retention curves (SWRCs), soil water thresholds (i.e., volumetric water content (θv) at saturation, field capacity (FC), and permanent wilting point (PWP); plant available water (PAW)), thermal conductivity (λ), and diffusivity (Dt) within the 0–20 cm soil depth. Forage systems included: Old World bluestem (Bothriochloa bladhii) + legumes (predominantly alfalfa (Medicago sativa)) (OWB-legume), native grass-mix (native), alfalfa + tall wheatgrass (Thinopyrum ponticum) (alfalfa-TW), and annual grass-mix (annual) pastures on a clay loam soil; and native, teff (Eragrostis tef), OWB-grazed, and OWB-ungrazed pastures on a sandy clay loam soil. The perennial OWB-legume and native pastures had increased soil organic matter (SOM) and reduced bulk density (ρb), improving ks, soil water thresholds, λ, and Dt, compared to annual teff and alfalfa-TW (P < 0.05). Soil λ, but not Dt, increased with increasing θv. Grazed pastures decreased ks and water retention compared to other treatments (P < 0.05), yet did not affect λ and Dt (P > 0.05), likely due to higher ρb and contact between particles. Greater λ and Dt at saturation and PWP in perennial versus annual pastures may be attributed to differing SOM and ρb, and some a priori differences in soil texture. Overall, our results suggest that perennial pasture systems are more beneficial than annual systems for soil water storage and heat movement in semiarid regions.