Yes, there are several online databases and platforms where you can access agricultural research papers for free. Some of them include:

1. ResearchGate:
ResearchGate is a social networking site for researchers and scientists. It allows researchers to share and access scientific papers across various disciplines, including agriculture. You can search for specific topics or authors, and many researchers upload their papers for free access.

2. Google Scholar:
Google Scholar is a widely used platform that indexes scholarly literature, including agricultural research papers. It provides a simple search interface, and you can filter results by relevance, date, and citations. While not all papers are freely available, Google Scholar often provides links to open access versions or preprints.

3. National Agricultural Library:
The National Agricultural Library (NAL) is a part of the United States Department of Agriculture (USDA) and offers an extensive collection of agricultural research papers. Their online database, AGRICOLA, provides access to articles, reports, and other resources related to agriculture and allied disciplines.

4. Directory of Open Access Journals (DOAJ):
DOAJ is an online directory that indexes and provides access to high-quality, peer-reviewed open access journals. It covers a wide range of disciplines, including agriculture. You can search for specific journals or browse through different categories to find relevant research papers.

5. Open Access Theses and Dissertations (OATD):
OATD is an index of freely available electronic theses and dissertations from around the world. It includes research papers from various disciplines, including agriculture. You can search by keywords, authors, universities, and countries to access relevant agricultural research papers.

6. EduRev:
EduRev is an online educational platform that provides access to a vast collection of study materials, including agricultural research papers. It offers a search function to find specific topics, and you can browse through different categories to explore relevant research papers.

Overall, these platforms and databases offer a wealth of agricultural research papers for free access. They provide researchers, students, and anyone interested in agriculture with valuable resources to stay updated with the latest advancements and findings in the field.