Abstract
In this paper, we investigated the effect of weeding at pre-seeding and soil pH on growth and yield of wheat which corresponded to the 16th cropping sequence in a serial experiment on no-tillage farming for eight years.
1) Soil water content of no-tillage plot (NT) measured at harvest time of wheat was higher than that of conventional tillage plot (CT) in 0-5cm layer, but the value of NT was lower than that of CT in 5-25cm layer. NT almost included the quantity of soil water as much as CT in a whole layer of 0-25cm, but a gradient of water content in the layer of NT differed from that of CT.
2) Soil bulk density of NT was lower than that of CT in 0-2cm layer, but the value of NT was higher than that of CT in 2-10cm layer. There was no difference in bulk density between CT and NT below 10cm.
3) pH (H2O) was not agreed with pH (KCl), but coefficient of correlation of 0.952 was obtained between NT and CT. We could not find the dense correlation among water content, bulk density, pH (H2O) and pH (KCl).
4) pH (H2O) of NT was lower than that of CT in 0-10cm layer, but the value of NT was higher than that of CT below 10cm.
5) Supplied lime had notably effect on wheat yield of NT, but the effect was not observed in CT. Lime was required about three years to take an effect after supplying on soil surface in NT.
6) Both treatments of herbicide and mechanical weeding at pre-seeding could not control vigorous weed growth and wheat yield in NT.
7) It seems that pH is one of the most effective factors on wheat yield in our long-term experiment.
