Soil Salinity is one of the main environmental factors that have a serious impact on crop production, and soil properties affect plant salt stress. As for the salinity in soil, it is common to measure soil electrical conductivity （EC） with a soil water suspension （1：5） because of its ease of measurement, on the while, another index, ECe is also measured using a saturated soil extract. In this study, NaCl was added to Masa soil （granite base material） with low humus content and CEC, and the comparison and relationship between EC and ECe were examined by a newly developed method. ECe increased even with a slight salinity, and the value was 19 times higher than EC（1：5）. In addition, when tomato was cultivated in Masa soil with four levels of NaCl, the Na concentration in the above-ground part of the tomato increased with the salt concentration, and the K/Na ratio and Ca/Na ratio decreased. Apparent salt damage symptoms were observed at EC 0.6 dS/m（ECe=10.8 dS/m）, and complete mortality at 0.8 dS/m（ECe=20.0 dS/m）, indicating that tomato salt damage is possible to occur in Masa soil. The Na concentration in the upper part of the plant top was higher than that in the lower part and the root. From the above, it appeared that ECe measured with saturated soil extract could detect salt concentration more sensitively and is more effective in predicting salt stress of tomato in Masa soil.
The effects of salt （NaCl） on soil electrical conductivity and ion elution were investigated in three Japanese soils （Masa soil, Andosol, and Jahgaru）, as well as the effects on tomato growth and absorption of inorganic components. The electrical conductivity （EC（1 : 5）） of the soil suspension and the saturated soil extraction （ECe） increased with salt addition with a high correlation efficiency. The conversion factor from the EC （1 : 5） value to the ECe value was 7.66 for Andosol and 7.08 for Jahgaru; however, Masa soil had a higher value of 18.1 and the soil was susceptible to salt damage. SEM-EDX analysis revealed an increase in Na and Cl concentrations and a decrease in Mg concentration in the surface of the Masa soil containing added salt.
Tomato growth was affected by adding salt（ EC（1 : 5）= 0 .75 d S / m）, and only the plants in the Masa soil died. Tomato growth responded according to ECe rather than EC（1 : 5）. In the Masa soil and Jahgaru, adding salt enhanced the release of Ca and Mg from the soil into the soil-saturated extract water. The concentration and composition of cations in the saturated soil extract strongly affected the inorganic salt composition in the tomato roots. In Jahgaru, the Ca concentration in the roots was high in response to the high Ca / Na ratio in the saturated soil extract. Compared with Masa soil, the Na concentration of the plant top in Jahgaru was suppressed, which may be caused by mitigation of Ca from Jahgaru.
This paper presents discussion of the influences of soil physical properties and power farming system on field vegetable cultivation by different drainage systems on upland fields converted from paddy fields near the Sea of Japan. Conversion of paddy fields with open ditches and mole drains to upland fields （B block） quickly and markedly improved soil physical properties, specifically the water permeability coefficient and uplandization index, compared to another field with an open ditch for soil structure development （A block）. Green soybean yields of first-year cultivation were 935 kg/10 a for A block and 732 kg/10 a for B block. Respective cabbage yields of second cultivation for the first year were 3,178 kg/10 a and 3,684 kg/10 a. Taro yields of second-year cultivation were 3,026 kg/10 a and 2,613 kg/10 a for quickly cultivated type and 2,539 kg/10 a and 2,364 kg/10 a for normal cultivation type. Welsh onion yields of third year cultivation were 4,464 kg/ 10 a and 7,107 kg/10 a. Upland fields converted from paddy near the Sea of Japan should have an open ditch and mole drain before vegetable cultivation. Then, first-year cultivation on upland fields can be expected to introduce green soybean using rotary tilling and a ridge-making implement by up-cut rotary processing, which can increase the pulverization rate and decrease water damage. Next, cultivation should introduce cabbage using rotary tilling and a small ridge-making implement, which might have a high work rate. From the second year, cultivation of upland fields should include taro and welsh onions using the ridge and mulching transplanter cultivation method, and a side-dressing fertilizer applicator ditcher cultivation method for wider use of the plow layer by the improvement of soil physical properties.
Hairy vetch （Vicia villosa Roth.） is often recommended as a green manure to relieve nitrogen （N） losses and to improve the performance of subsequent corn （Zea mays L.） in cropping systems. However, it is unclear whether hairy vetch impacts phosphorus （P）-mobilizing capacity and P availability of corn. Therefore, the aim of this 2-year field study is to determine the impact of hairy vetch cropping on the P-mobilizing capacity （phosphatase activity）, P uptake, and yield of subsequent silage corn. Throughout the study period, cultivation of hairy vetch increased EC, NO3−N, ACP, and ALP activities compared with those treated with fallow. In addition, under the hairy vetch treatment, the plant length and stem diameter at the V6 stage in 2017, and leaf area index of the corn at the V6 stage in 2016 tended to be higher than those under the fallow treatment. P uptake in the corn under the hairy vetch treatment at the V6 and R1 stages tended to be higher than that under the fallow treatment. Moreover, under the hairy vetch treatment in 2016, the grain yield, grain number, and 100-seed weight of corn tended to be higher than those under the fallow treatment. However, the grain yield and yield components were not changed between hairy vetch and fallow treatments in 2017. Taken together, these findings suggest that soil biochemical properties, such as soil phosphatase activity, can be associated with P-mobilization arising from cultivation of hairy vetch, leading to increased growth and yield of subsequent corn in this study. Further research to improve the P availability, growth and yield of subsequent corn is needed to determine optimal hairy vetch cropping systems.
To increase the yield of one-year-old asparagus stocks grown in open field culture, a longer period for stock cultivation is required. The purpose of this study is to clarify the shape of holes appropriate for the early planting of asparagus. In the present study, plug seedlings were planted in five holes of different shapes, and the temperatures of the holes and growth were compared. The chilling hours less than 5℃were the most in the funnel-form holes II, followed by the conventional hole, the funnel-form holes I, the reverse bottle holes and cylindrical hole. The growth of seedlings planted in the reverse bottle holes was higher than that of seedlings planted in other holes. Therefore, the shape of the reverse bottle holes is the most appropriate for the early planting of asparagus.