High Moisture Treatment Research Articles

Effects of Soil Moisture on Soil pCO2, Soil Solution Bicarbonate, and Iron Chlorosis in Soybeans

AbstractFour pot experiments were performed with five calcareous soils from western Minnesota (Haplaquolls and Calciaquolls) to determine the effects of soil moisture and soil temperature on Fe chlorosis in soybeans [Glycine max (L.) Merr.]. We used a factorial design with gravimetric moisture contents and bulk density values ranging from 0.22 to 0.44 kg kg−1 and 1.14 to 1.38 Mg m−3, respectively. Factor combinations of these levels resulted in ranges of volumetric moisture contents from 0.27 to 0.54 m3 m−3, air filled porosity fractions from 0.27 to 0.00, and soil matric potentials from <‐1500 to near 0 kPa. The soil pCO2 contents measured from gas wells in pots increased from 0.16 to 1.64 cmol mol−1 as a result of decreased gas diffusion when the air‐filled porosity decreased. With increasing soil moisture, soil solution HCO‐3 concentrations attained values as high as 10 mM. Total chlorophyll (ChlT) contents of Anoka soybeans decreased as soil moisture, soil pCO2, and soil solution HCO‐3 increased. The same response was not observed in all calcareous soils. Calcareous soils with lower amounts of clay sized CaCO3, lower soil solution Mg2+, and/or lower bicarbonate extractable P did not produce as severe a chlorosis with increased moisture. This suggests that clay sized CaCO3, Mg, or P may be additional stress factors associated with HCO‐3 induced chlorosis. High soil moisture treatments on a calcareous soil provided an effective soil screen for differentiating between susceptible and nonsusceptible soybean cultivars. Soil temperatures of 12 and 26°C produced more chlorosis at a given soil moisture than at 16 or 19°C. Soil temperature appears to be an additional stress factor, which might explain some of the variability in the incidence of Fe chlorosis under field conditions.

Effect of soil moisture on the response of subterranean clover to lime

A pot experiment was carried out using a soil high in aluminium to investigate the relationship between the dry matter responses of subterranean clover to lime at two soil moisture levels. Subterranean clover, which is reputed to be tolerant to high aluminium levels in the soil, showed an increase in the dry weight of plant tops of 50% when lime was added on the low moisture treatments. By contrast the response on the high moisture treatment was only 5.6%.

Selection in Alfalfa for Forage Yield with Three Moisture Levels in Drought Boxes1

Although soil moisture availability is the most limiting factor in crop production in many areas of the United States, little progress has been made in developing cultivars tolerant to moisture stress. The objective of our study was to evaluate a drought box screening procedure for use in alfalfa (Medicago sativa L.) breeding to improve performance under less than optimum moisture conditions. Seven diverse alfalfa cultivars and three germplasm sources were evaluated for forage yield and root characteristics under three moisture treatments in drought boxes in a shadehouse. Divergent selection for forage yield was practiced in the low and intermediate moisture treatments, and for high forage yield in the high moisture treatment. Selected plants were intercrossed within groups and progenies were evaluated under similar conditions. Average forage yield was reduced 30 and 55% in the intermediate and low moisture treatments, respectively, when compared to the high moisture treatment. Entries did not differ for yield in the low moisture treatment, but they varied in their yield response to increasing rates of irrigation. Variability among plants for forage yield was not reduced by moisture treatments. Root weight decreased and root fibrousness increased as moisture stress increased. Entries differed for all root characteristics measured. Forage yield was correlated with all root characteristics, but we concluded that the added information did not justify the time, labor, and expense of root excavation. Selection and evaluation in the intermediate moisture treatment resulted in the greatest progress and differentiation among populations.

Effect of moisture level on the root pattern of Alfalfa

There have been a few investigations on the effect of moisture on root development of alfalfa (Medicago sativa L.), but none have attempted to describe the relationships in a quantitative manner. Therefore, alfalfa root patterns along with yield and evapotranspiration (ET) were examined under different moisture levels, using a line-source sprinkler system. Water application ranged from 28 to 153 cm, the latter representing the potential evapotranspiration. Alfalfa root mass and yield were highest under high moisture levels, and the shoot/root ratio increased with increasing moisture level. The relationships between ET and root mass and between ET and shoot/root ratio were curvilinear. The largest percentage of root mass under all moisture treatments was found in the top 45 cm of the soil profile where the largest differences in total root mass between treatments were observed. The percentages of roots at each soil depth averaged over three ranges of moisture levels were curvilinear functions of soil depth. Although alfalfa roots were found to a depth of at least 150 cm for all moisture levels, there was a greater rooting depth with a higher moisture level. Roots were detected to a depth of 210 cm for the high moisture treatment, although root biomass was small below 170 cm where a sand layer was encountered which may have impeded root penetration. The root diameter was found to be independent of moisture level, which means that there was a greater root surface area with higher moisture levels. Root length density distribution was similar to root mass distribution.

Water Use by Cotton From Low and Moderately Saline Static Water Tables1

AbstractA 4‐year lysimeter study was conducted to determine the contribution of low to moderately saline, shallow static water tables to the total water use and yield of cotton grown on deep, permeable soils. Water tables controlled at 91‐, 183‐, and 274‐cm depths contributed 54.4, 26.4, and 17.3% of the total water use under the high moisture treatment and 60.6, 48.9, and 39.2% under the low moisture treatment. Total water use consisted of soil profile depletion, rainfall, irrigations, and additions of water to maintain the water tables. Water uptake from the 274‐cm water table was strongly related to the salinity level (electrical conductivity of saturated soil extract, ECe) of the capillary (183‐ to 274‐cm) zone. Lint cotton yields were related to the total amount of water obtained from the table as well as to the salinity level of the capillary zone. Moderate salinity (ECe of 10 to 14 mmhos/cm) of the capillary zone reduced monthly and seasonal water use from the water tables as compared with low salinity (ECe of 2 to 3 mmhos/cm) conditions. The high moisture treatment delayed significant use of water from 183‐ and 274‐cm water tables until late in the season, when irrigations were discontinued and the upper soil profile dried.

Effects of Soil Moisture, Temperature, and Fertility on Yield and Quality of Irrigated Potatoes in the Southern Plains1

SynopsisManagement of soil moisture by irrigation techniques influenced soil temperature and yield and quality of potatoes. The minimum soil temperature and the highest yield occurred in the every‐row irrigated high moisture treatment. Fertility rates higher than 80‐0‐0 or distance along the irrigation run did not influence tuber yield and grade.