The important parameters are soil organic matter and its fractions. Check out the following article that will soon be out:

Environmental Monitoring and Assessment

DOI: 10.1007/s10661-017-5881-y

Title: Soil organic matter as sole indicator of soil degradation

Thanks very much Dr Sunday

By looking at the value of integrated soil quality index which is calculated based on soil organic matter content, Microbial biomass C, bulk density and water holding capacity can indicate the sustainability of cropping system. I will explore the article and inform you later.

Thanks Dear Dr Haile

In my opinion, if a farmer adopts the recommended cropping system by the research scientists/institutes, then it is sustainable otherwise........................................ 

I think, it may be interesting to read the article:

REIG, E.; AZNAR, J.; ESTRUCH, V.. A comparative analysis of the sustainability of rice cultivation technologies using the analytic network process. Spanish Journal of Agricultural Research, [S.l.], v. 8, n. 2, p. 273-284, july 2010. ISSN 2171-9292. Available at: . Date accessed: 20 mar. 2017. doi:http://dx.doi.org/10.5424/sjar/2010082-1200. DOI: 10.5424/sjar/2010082-1200

Thanks dear Dr Vicent

Sustainability can be taken from different yet the parameters has to address from point of income generation (wealth creation); food security; nutritional contribution to the HH; productivity (this can address issues of lad fertility, environmental friend, organic and healthy production et); etc.

Specifically variable like sale price, cost of production, input price, yield, adaptation methods, variety type, could help to view the wealth creation capacity or comparable advantage and absolute benefit for sustainability will be forecast for future trend analysis.       

There are three categories of parameters to look at when measuring the sustainability of a system:

Category 1: Environmental parameters,

Category 2: Economic parameters

Category 3: Social parameteres

So depending of the objective of your study, you may need to select appropriate paramters from the above three categories to ensure that at least each category is represented in your study. On another hand, you may be interested in looking at only one or two of the sustainability aspects, siuch as environmental sustainability, economic sustainability or social sustainability. this depend on the available resources to carry out the measurement.