Effect of litter type on growth and nutrient content of perennial grasses
Biomass, cover, density, height and concentrations of N, P, C, Fe, Mn, Cu and Zn were evaluated in Sporobolus crvptandrus and Eragrostis lehmanniana at flowering and at seed ripening stage to determine whether these attributes are affected by the type of litter used or by litter treatment. Annual rye, California poppy and rye-poppy mixture were the sources of litter while litter treatments included removing organic residue, leaving organic residue standing or roto-tilling organic residue into the surface soil. The effect of litter type and litter treatment on the soil was evaluated. A parallel greenhouse experiment was carried out. Results indicate that California poppy contained a higher level of all nutrients studied compared to annual rye and contained about twice the concentrations of N, ~~~ Zn and Fe. For both annuals and perennials, the nutrient content generally decreased between flowering and seed ripening with annuals indicating more decline than perennial grasses. The greatest decline was observed for N in California poppy. Field observationconfirmed that the non-lignified California poppy shoots broke down faster than culms of annual rye. x xi Biomass production in Sporobolus and Eraqrostis was unaffected by litter type. However, for both species the highest biomass was obtained in the tilled treatment. Litter tilling produced more vigorous and healthier plants compared to other treatments. Except for P, nutrient concentrations were largely unaffected by litter type. The highest P concentrations were consistently obtained from perennial plants grown in annual rye plots. Fe and Cu concentrations were consistently higher in the tilled treatment. C and P appeared unaffected by litter treatment. N, Mn and Zn concentrations were more variable and more difficult to categorize. In soil samples, all nutrient concentrations were higher at the end of the study than at the beginning. Litter source appeared to have minimum effect on nutrient concentration while tilled treatment was superior to standing which was superior to the removed treatment .