Relationship between soil physicochemical properties and the growth and yield of wheat cultivar 'Sanukinoyume2009' for Japanese noodles

To identify factors inhibiting the improvement of wheat yield, we analyzed the relationship between soil physicochemical properties and the growth and yield of 'Sanukinoyume2009 wheat' in individual fields. Significant correlations were observed between growth/yield of 'Sanukinoyume2009' and sediment volume, soil hardness, and Fesub(o)/Fesub(d) ratio, all of which are physical properties of soil closely related to soil moisture. Growth and yield were negatively correlated with sediment volume and Fesub(o)/Fesub(d) ratio and positively correlated with soil hardness. Sediment volume and Fesub(o)/Fesub(d) ratio were also higher in fields used for rice-wheat double cropping than for fields used exclusively for continuous wheat cropping. Furthermore, yield tends to be lower when rainfall in the November sowing season is high, indicating that drainage prior to sowing is important in fields with high sediment volumes or those in which rice was the previous crop. Regarding soil chemical properties, we found a significant positive correlation between soil pH and yield. We speculate that, when pH is low, inorganic component content is also low, leading to reduced yield. Furthermore, fields with high total carbon content tend to also have high available nitrogen content, resulting in sustained supply of nitrogen in the latter half of the growing season. Fields with high carbon content are also rich in phosphate and boron, both of which were positively correlated with yield, indicating that high carbon content increases yield. Both pH and total carbon content tended to be lower in fields used for continuous wheat cropping than in fields used for rice-wheat double cropping; this suggests there is a need to incorporate organic matter or other material for soil improvement in fields with low pH or total carbon content, and particularly in fields used for continuous wheat cropping.