RESEARCH ARTICLE Short-Term and Long-Term Effects of Soil Ripping, Seeding, and Fertilization on the Restoration of a Tropical Rangeland David Kinyua, 1,2 Lauren E. McGeoch, 1,3 Nicholas Georgiadis, 1,4 and Truman P. Young 1,3,5 Abstract Rangeland degradation is a serious problem in semiarid Africa. Extensive areas of bare, compacted, nutrient-poor soils limit the productivity and biodiversity of many areas. We conducted a set of restoration experiments in which all eight combinations of soil tilling, fertilization, and seeding with native perennial grasses were carried out in repli- cated plots. After 6 months, little aboveground biomass was produced in plots without tilling, regardless of seeding or fertilization. Tilling alone tripled plant biomass, mostly of herbaceous forbs and annual grasses. Perennial grasses were essentially limited to plots that were both tilled and seeded. The addition of fertilizer had no significant addi- tional effects. After 7 years, vegetation had declined, but there were still large differences among treatments. After 10 years, one tilled (and seeded) plot had reverted to bare ground, but the other tilled plots still had substantial veg- etation. Only one seeded grass (Cenchrus ciliaris ) was still a contributor to total cover after 10 years. We suggest that restoration efforts on these soils be directed first to breaking up the surface crust, and second to the addi- tion of desirable seed. A simple ripping trial inspired by this experiment showed considerable promise as a low-cost restoration technique. Key words: degradation, East Africa, infiltration, Kenya, Laikipia, overgrazing, rehabilitation, ripping. Introduction Approximately one-quarter of the Earth’s surface is devoted to managed grazing (Asner et al. 2004). In semiarid rangelands, the interaction of heavy grazing and climatic variability can cause dramatic ecological degradation (Asner et al. 2004; Wes- sels et al. 2007). Despite extensive research on the causes and consequences of rangeland degradation, studies on rangeland restoration are less common, and findings are often anecdotal or context dependent (King & Hobbs 2006). In East Africa, rangeland degradation is serious and pervasive, but inves- tigations of rangeland restoration have been especially rare (Descheemaeker et al. 2006; King & Stanton 2008). Here, we present an experimental investigation of the relative ability of three common restoration techniques to generate long-term rangeland improvements in a semiarid Kenyan savanna. Heavy grazing initially alters vegetation composition and decreases primary productivity, especially of palatable species 1 Mpala Research Centre, PO Box 555, Nanyuki, Kenya 2 USAID East Africa, PO Box 629, Village Market 00621, Nairobi, Kenya 3 Department of Plant Sciences, University of California, Davis, CA 95616, U.S.A. 4 PERC, 2048 Analysis Drive, Bozeman, MT 59718, U.S.A. 5 Address correspondence to T. P. Young, email tpyoung@ucdavis.edu  2009 Society for Ecological Restoration International doi: 10.1111/j.1526-100X.2009.00594.x (Yates et al. 2000; Simons & Allsopp 2007). By reducing native species diversity and increasing the exposure of bare ground, heavy grazing can decrease community resilience and initiate damaging positive feedbacks (van de Koppel et al. 1997). For example, reduced vegetation cover can lead to reduced microtopography, increased runoff, and increased ero- sion, which in turn can lead to reduced seed retention, water availability, nutrient retention, and plant establishment (Jones & Esler 2004; Descheemaeker et al. 2006; Mati et al. 2006). Once bare ground is exposed, livestock and raindrops can cause soil compaction and reduce soil aggregate stability. Eventually, such structural degradation can lead to the forma- tion of a surface seal that further reduces infiltration and hin- ders seed germination (Beukes & Cowling 2003). In Eastern and Southern Africa, many rangelands are now pockmarked by large bare areas with minimal organic matter and a smooth, sealed surface crust (van der Merwe & Kellner 1999). This study focuses on the restoration of such severely degraded areas, in particular on the goal of increasing vegetative cover. Semiarid African rangelands are often characterized by threshold dynamics and alternate stable states that are highly resilient (Ellis & Swift 1988; Milton et al. 1994; Todd 2006). In this context, severely degraded rangelands can be viewed as lands that have undergone dramatic state shifts or thresh- old transitions (Milton & Dean 1995; van de Koppel et al. 1997; Bestelmeyer 2006). For the restoration of these lands, passive methods (e.g., the removal of livestock) are usually 226 Restoration Ecology Vol. 18, No. S1, pp. 226–233 SEPTEMBER 2010