Maharjan Lab

Sujani De Silva, Dipak Santra, Cody F. Creech et al.

Polymer Coated Urea (PCU) improves mint yield and also reduces nitrous oxide emission

Lithma Kariyawasam Hetti Gamage, Saurav Das, Mitchell Stephenson et al.

Croplands at sites with manuring and no-till recorded lower soil organic matter depletion from reference-site levels (28%) than sites under continued conventional management.

Bijesh Maharjan, Saurav Das, Vesh R. Thapa et al.

The soil health cycle is proposed as a soil health management cycle encompassing human dimensions, management practices, and their effects on soil health indicators, leading to subsequent impacts on soil functions.

Saurav Das, Aaron Hird, Bijesh Maharjan et al.

Comparative soil health studies are critical in soil conservation and gauging the success of different management practices in soil health improvement. A primary challenge in these studies is the selection of a consistent natural reference site. Current choices vary widely, from minimally disturbed areas to pristine prairies. This methodological paper underscores the need for deliberate and thoughtful reference site selection for benchmark soil properties. Utilizing the State &Transition models, the study introduces a framework for this selection, drawing upon the ecological site (ES) and reference plant communities detailed in an ecological site description (ESD) within a respective Major Land Resource Area (MLRA). This study advocates for a localized classification within the framework of the Cropland Reference Ecological Unit (CREU), emphasizing the significance of local precipitation and soil data to ensure unbiased comparisons. Soil samples from eastern (MLRA 106) and western (MLRA 67A) Nebraska were collected, representing distinct pedogenetic and climatic differences. Analysis of soil organic matter between MLRAs displayed substantial variations, suggesting potential biases and complexities in soil health gap calculations when using reference sites and croplands not in the same MLRA, soil types (texture class), or precipitation zones. However, refining the comparisons by delineating the MLRA, soil, and precipitation zones within the framework of CREU yielded more consistent and realistic comparative data. Integrating the MLRA and ES, complemented by granular soil and precipitation data, provides a robust method for establishing soil health benchmark data.

Bijesh Maharjan, Saurav Das, Bharat Sharma Acharya

Growing calls and the need for sustainable agriculture have brought deserved attention to soil and to efforts towards improving or maintaining soil health. Numerous research and field experiments report soil health in terms of physicochemical and biological indicators, and identify different management practices that can improve it. However, the question remains how much of cultivated land has degraded since the dawn of agriculture? What is the maximum or realistically attainable soil health goal? Determination of a benchmark that defines the true magnitude of degradation and simultaneously sets potential soil health goals will optimize efforts in improving soil health using different practices. In this paper, we discuss a new term “Soil Health Gap” that is defined as the difference between soil health in an undisturbed native soil and current soil health in a cropland in a given agroecosystem. Soil Health Gap can be determined based on a general or specific soil property such as soil carbon. Soil organic carbon were measured at native grassland, no-till, conventionally tilled, and subsoil exposed farmlands. Soil Health Gap based on soil organic carbon was in order of no-till < conventional till < subsoil exposed farmland and subsequently, maximum attainable soil health goal with introduction of conservation practices would vary by an existing management practice or condition. Soil Health Gap establishes a benchmark for soil health management decisions and goals and can be scaled up from site-specific to regional to global scale.