Interconnection of altitude of stationary GPS observation points and soil moisture with formation of winter wheat grain yield
Institute of Soil and Plant Science, Latvia University of Agriculture, Liela iela 2,Jelgava, LV-3001, Latvia; e-mail: Gundega.Dinaburga@llu.lv
Field trials were carried out at the Research and Study farm “Vecauce” of the Latvian University of Agriculture during the years 2006–07 to investigate factors influencing the formation of the winter wheat grain yield. Researches have been carried out in stationary observation points. Results show tight negative correlation between the altitude of observation points and soil moisture. The correlation is significant P < 0.05 in both trial years but coherence is tighter in the year with reduced precipitation, as observed in April–July 2006. Significant negative correlation was established between altitude and winter wheat grain yield. In year 2006, when lack of precipitation was observed, this coherence is with increased probability P < 0.01. Soil moisture at the depth of 40−45 cm was below optimum – 25% – in both trial years and also in both stationary observation levels with average altitude 95 and 102 m above sea level. It was also significantly lower in the highest points of the terrain. Significantly higher grain yield of winter wheat was obtained in field points with an average altitude 95 m above sea level. This coherence is also more explicit in the year with less precipitation, as in 2006. Analysis of correlation established that soil moisture at the depth of 40−45 cm has significant positive impact on the winter wheat grain yield and on the flag leaf area.