Soil Sensing and Smart Farming

By Botros George, Senior Director – Product Development

Soil is arguably the most important resource for our world, as it supplies the majority of our nutritional needs. We can make do without meat, but the world’s population of 9 billion must have access to plants and plant-based foodstuffs supplied by our soil in agricultural settings. Yet non-stop farming can cause soil to become depleted of nutrients that enable plant growth.

On average 60 percent of crop yields depend on soil fertility. Soil degradation is a threat to all farmers. It is estimated that each year 24 billion tons of fertile soil are lost due to erosion as a result of unbalanced soil management and the consequences of overutilization. Because soil restoration is a difficult, costly and time-consuming process, effective soil management is needed before damage occurs.

On top of this, climate change is creating hotter, more arid areas, even in the basin of agricultural civilization such as Iran. Soil is the largest repository of carbon in our world, and the soil’s capacity to store carbon is even greater than that of vegetation and the atmosphere. At the same time organic carbon is the key to soil health and resilience. Soil carbon plays a key role in supplying macro- and micro-nutrients to plants and can even help stabilize the soil against mechanical impact, offering protection against extreme climate events.

New Soil Sensing Technologies for Timely Decisions: No More Central Lab Delays

How can we better manage the soil to ensure that we maintain the carbon content and the additional nutrients that can keep it healthy? Soil analysis – as part of smart farming — is a must. Current soil measurement techniques can be accurate but may take days. The process involves collecting the sample correctly, taking or sending samples to an agricultural extension lab that has a knowledge of soil analysis, and waiting for the results to come back. At this point it may be too late. A farmer determining when to plant may make an uninformed decision at the cost of a reduced crop yield.

A better solution is to use newly available technology that can assist in immediate decisions and eliminate the need to send samples to a lab. Soil analysis using handheld spectral sensing offers the opportunity for farmers to see the results of any soil analysis instantly. The NeoSpectra-Scanner and the NeoSpectra- Micro (integrated into a handheld system) both offer the ability to scan soil samples in the field or in farm offices.

NeoSpectra solutions can accurately identify and quantify soil nutrients. Systems have been validated to analyze for multiple nutrients in soil, including nitrogen, phosphorus, and potassium as key indicators.

The sensor products are easy to use, requiring no training.  For agricultural staff using pre-programmed applications, the process is simply point and shoot. The results appear within seconds on a smart phone, enabling farm managers to determine soil condition. For custom applications, the NeoSpectra-Scanner, which is hardware- and software-ready, offers a straight-forward five-step process for application development.

The developer collects sample materials, make measurements by characterizing samples with a reference method, collect spectra by measuring the samples using the scanner, and then develop analysis models that correlate spectra data to reference measurements. The final step is to validate and deploy the application.

Measuring Soil Carbon to Ascertain World Soil Health 

Recognizing the importance of soil carbon, the Lima-Paris Action Agenda set forth a goal to increase global stocks of soil organic matter by 0.4% percent per year to compensate for human-caused emissions of greenhouse gases. But a crucial element in this plan is the ability to accurately estimate the size of the soil carbon pool. To understand and map the distribution of soil carbon stock requires rapid, accurate and cost-effective means of measurement that can be deployed in the field.

While near infrared technology (NIR) has become an important tool in soil research, research-grade NIR spectrometers cost from US$40,000 to US$60,000, and sending samples to a lab means days or weeks before receiving data.

Gauging carbon content with a handheld sensor has been proven almost equivalent. In fact, a handheld NIR scanner incorporating the NeoSpectra-Micro was used in a large scale study in Australia (Budiman et al., 2019), where 151 diverse soil profiles were collected from an agricultural area in New South Wales to build predictive models for total Carbon (TC) by a research-grade ultraviolet-visible-NIR (Vis-NIR) spectrometer and the NeoSpectra sensor for total carbon. A subset of 24 soil profiles was used to test predictions for organic carbon (OC).  The models cross validation results showed that the NeoSpectra sensor can predict organic carbon with an accuracy of RMSE = 0.16% and R2 = 0.78. For total Carbon, it was able to predict it with an accuracy of RMSE = 0.5% and R2 = 0.70. The study concluded that the NeoSpectra sensor results were comparable to those of the high-end device, and that less costly devices such as the NeoSpectra sensor provides high potential for soil analysis.

We see the use of handheld spectral sensing is a core technology for smart farming and soil preservation that can help farmers and soil scientists around the world as we seek to boost production and protect the environment.