Effect of Stubble Grazing, Tillage and No-till Seeder Type on Pea/Barley Forage Productivity and Botanical Composition.

Crop stubbles are the major feed source for small ruminants during summer in the southern Mediterranean. Heavy stubble grazing, however, leaves little or no residue on soil surface, increases soil compaction hence may impede the successful implementation of conservation agriculture. The objective of this trial was to investigate the effect of stubble grazing and tillage on soil quality, crop productivity and no-till seeder compatibility. An experiment was established in Setif, Algeria in 2014 (average annual precipitation 400 mm) using pea/barley (Pisum Sativum cv. Sefrou/Hordeum vulgare cv. Tichedrett) forage mixture seeded into grazed barley stubble. Here we report on the first year dry matter production of the trial. Main plots were stubble management (grazing versus no grazing) and the sub plots were tillage (tilled versus no-till) and seeder type (disk versus tine seeders). Barley stubble was grazed intensively (2000 sheep d ha-1) for 2 days by Ouled Jellal yearling ewes leaving 0.8 t ha-1 stubble on soil surface after grazing. Grazing, tillage and seeder type had no effect on total forage dry matter production. However, there were significant differences for botanical composition. Barley produced more dry matter (p = 0.083) in ungrazed plots (5.1 t ha-1) than grazed plots (4.3 t ha-1), and also under tillage (5.8 t ha-1) than no-till (4.1 t ha-1). Pea dry matter was the lowest (P < 0.05) under no-till when seeded with disk seeder (0.4 t ha-1) and the highest in tine and tilled treatments; 1 and 1.1 t ha-1 respectively. Similarly, weed dry matter was the greatest under no-till when seeded with disk seeder (3.3 t ha-1) and the lowest when seeded with tine seeder (1.7 t ha-1) and after tillage (1.4 t ha-1). Overall grazing appeared to have little impact on no-till seeded forage crops when tine seeder was used.