Depends on wether you are using pretreated and enzymatic hydrolysed agriculture residue or untreated one. Also for what purpose you are using your agriculture residue? Is it for methane or any other by product? For biogas production from untreated agriculture residue you can use wastewater/Deep soil (littered) soil/ anaerobic digestate etc as a source for developing anaerobic inoculum. Try not to sterlize your agriculture residue while using as substrate. It will pretreat you residue, increase your cost and kill your potential microbes on lignocellulosic residue capableof anaerobic digestion. There are many thing you can do but you need to be more clear on your question and provide more information on what you actually want.
If you want to know about the anaerobic technologies about developing inoculum than the information is quite vast and you need to be more specific. if you need any help than give a bit detail about your requirements.
As is known, ruminant animals use their organs that so-called rumen to digest cellulosic wastes. The bacteria present in these organs have enzymes that degrade lignino-cellulosic substances. You should logically use these kinds of animals. If you have slaughterhouses nearby somewhere, you can get these suitable samples. Another way is to provide waste sludge from an anaerobic digestion tank. In any case, a few months or even more adaptation periods can be necessary. We recommend a mesophilic conditions as a starting point. However, if you are working in lab scale you can choose ruminants. It seems more sensible to supply waste sludge if you are working full-scale. Despite everything, this is a research. It will wait for the difficulties you did not expect.
I think using ruminant bacteria as inoculum is a good thing as it digested lignocellulose and might excrete cellulase, and make sure temperature is maintained at ruminant environment to have a fast degradation.
Here in INSA Lyon in France we work on exactely the same material. We use some of sludge (taken from WWTP) to accelerate the culture devlopement. It takes about 20 days in anaerobic conditions with about 55 °C.
To gice you an exact answer is not possible, because it is not clear from your question what is the purpose of your anaerobuic digestion and it is not clear if you think about solid state fermentaionb or about digestion in suspension. Nevertheless, all above recommendations are OK. From my experience we acclimatized an anaerobic inoculum for anaerobic pretreatment of wastewater from a coking plant between 21 and 38 days.
We are using rumen to ferment cellulosic waste. Generally it takes between 2 to 30 days to transition the microbial ecosystem to a new feedstock. The transition time is dependent on the original feedstock of the animal and the differences in the new feedstock and the nutrient mix being used to enhance the process.