EFFECT OF TILLAGE AND N FERTILIZATION OF A SOLONETZIC SOIL ON BARLEY PRODUCTION AND SOME SOIL PROPERTIES

Solonetzic soils have generally shallow Ap horizon and any loss of surface soil can result in serious reduction in total and sustained crop production. Zero or minimum tillage has been shown to reduce soil erosion, but information on the feasibility of reduced tillage systems on Solonetzic soils in Alberta is lacking. A field experiment was conducted from the fall of 1981 to the fall of 1989 on a Solonetzic soil complex at Vegreville in east-central Alberta, to determine the effect of tillage and N rate on spring barley yields and some soil properties. There were three tillage treatments (zero tillage - ZT, minimum tillage - MT and conventional tillage - CT) and four rates of fertilizer N (0, 40, 80 and 120 kg N ha-1 first applied in 1983). The MT treatment received one cultivation prior to sowing, while the CT treatments received one cultivation in fall and another in spring prior to sowing. The N fertilizer (ammonium nitrate) was broadcast on soil surface following sowing on all plots except the control without N. Tillage had no effect on grain yield of barley, but had a significant effect on straw and grain plus straw (whole plant) yield. The yield differences between ZT and CT were slightly greater at 40 and 80 kg N ha-1 than at the 120 kg N ha-1 rate. Nitrogen fertilizer had a significant effect on grain, straw and whole plant yield. The N concentration in grain and straw increased, while P concentration decreased with increasing N rate. Conventional tillage yielded generally higher total N and slightly lower P concentration in barley than ZT. Soil had more moisture in spring under ZT than under CT in 2 of the 3 years studied. The greater strength ( 1.1-1.3 MPa) at the 0-10 cm soil depth under ZT and MT, compared with CT, did not adversely influence crop yield. Tillage and added N had no effect on extractable NH4-N, P, K and SO4-S in soil, but NO3-N in soil increased with N rate. Apparently, there was little or no leaching of NO3-N below the 60 cm depth. In conclusion, ZT and or MT produced crop yields comparable or superior to those under CT on a Solonetzic soil, and also improved soil water conservation.