The effects of soil tillage systems were evaluated on soil aggregate mean diameter (DMA), soil surface cover (CSS), deep-ploughed soil layer (PCA) and potato tuber yield. Two experiments, one sprinkle-irrigated and the other drip-irrigated, were conducted in a clay soil with the same treatments. The treatments were: T1 = no tillage, except furrowing before planting, also performed in the other treatments; T2 = one sub soiling (SS); T3 = twice rotary hoeing (ER); T4 = one disc plowing (AD) + twice disc harrow leveling (GN); T5 = 1AD + 2GN + 1ER; T6 = 1AD + 2GN + 2ER; T7 = 1SS + T6 sequence; T8 = one moldboard plowing (AA) + 2GN. Treatments were arranged in a randomized block design with four replications. Planting was manually performed, in previously open furrows. The highest DMA and CSS values were obtained at T1 and T2 and the highest PCA value, 29.6 cm, was observed at T8. In both experiments, commercial tuber yield was the largest in T8, the smallest in T1 and T2, and intermediate in the remaining treatments. In both experiments, the commercial tuber yield increased 52% due to moldboard plow (T8) in comparison to disk plow (T4).
Solanum tuberosum; direct seeding; soil conservation; moldboard; rotary hoe; drip; sprinkle
