2 Corinthians 5:21 (GW) God had Christ, who was sinless, take our sin so that we might receive God’s approval through him.
The best exchange ever!
One of the most confusing, headache–provoking, abstract concepts in soil science is cation exchange capacity (CEC). I can still remember thinking when I first learned about CEC in my first soil science course as a sophomore in college, “Just how am I supposed to understand this anyway?”. I also had similar thoughts in subsequent advanced soil science courses as an undergraduate and graduate student. Then the first time I taught this concept as a newly-minted instructor, I can remember thinking “If I can’t understand this myself, how in the world can I teach this to my students?”. And now, almost 25 years later, I am still over here grinding my teeth with a churning stomach from the stress of trying to explain this concept while writing this essay.
Yet the older I get, the more I value the products of good, solid, hard work, so let’s plunge in together into the deep end of both soil science and Scriptural thought and unearth some beautiful truths for ourselves. (Yes, thank you for holding my hand – it does help to jump into these ideas together as friends!)
CEC is an indispensable function of a healthy soil. It gives soil the ability to provide essential nutrients to a growing crop, both at the time of fertilizer application and throughout the growing season and/or life of the plants. It also is vital in its keeping a soil’s pH level relatively constant over time (also known as buffering). Soil is naturally negatively charged which means it attracts the positively charged plant-essential nutrients and holds onto them, as according to the basic chemical principle of “opposites attract and likes repulse”. (I will restrain myself at this time from giving forth on this concept in human relationships!) Even if sufficient plant nutrients for the entire growing season are applied in fertilizer (be it an organic source or not), these nutrients will not be provided to the crop as it grows without the action of CEC in soil. Without CEC, these nutrients would either be washed off the soil surface or down through the soil profile by rain or irrigation waters. If this occurs, then other potentially worse problems of offsite pollution of surrounding water bodies and/or natural habitats can result. And we can’t fail to include those monies lost: by the farmer(s) who paid for the fertilizer application; from loss of crop productivity, and that required for amelioration of the polluted systems.
A soil’s CEC primarily comes from the clay and the soil organic matter (SOM) fractions. The larger sand and silt particles provide some CEC but to a much lesser extent because of their lower surface area to volume ratio and decreased amount of overall net negative charge. Since the clay and SOM fractions are so tiny in size but huge in negatively charged surfaces, they are ideal environments for thousands of simultaneous chemical reactions. Plus, the clays have vast amounts of internal area because the clay structure is like that of stacked dinner plates. Reactions can occur not just on the outside of the clays but on all of the surfaces in between the “plates” or elliptically shaped clay minerals themselves. Also, the clay “plates” can expand and contract to absorb or release chemicals in response to chemical concentrations around them.
It is these chemical concentrations that are the driving force for the chemical reactions occurring during cation exchange. Just as materials flow naturally from areas of high concentration to areas of low concentration along a diffusion gradient, the chemicals being exchanged in CEC reactions do the same. Almost as if the soil is “pumping” out positively charged plant nutrient ions from where they are in high concentration on the clays/SOM to go to the areas of low concentration around the actively growing plant roots. The concentrations are low around the plant roots because the roots are taking in the nutrients for use in metabolism and growth. And in turn, the soil is taking up those chemicals the plant roots are “pumping” out as waste. Hence, the terminology of cation exchange.
This same principle of exchange also applies to the soil’s natural pH buffering capacity in the soil absorbing hydrogen ions (H+) from the soil solution while emitting calcium and other buffering ions as to keep the pH closer to neutral. Thus, CEC acts as a natural means of allaying soil acidification in a soil as it weathers (or “ages”) over time (or in other words, as the soil loses more of its negative charge). This buffering helps to keep the plant essential nutrients in forms the plant can absorb and use for growth. An acid pH in soil can cause some plant nutrients to change into forms the plant can’t use while also creating an environment favorable for toxic levels of detrimental non-plant nutrient ions in the soil. These issues related to soil pH are especially prevalent in soils in the Southeastern U.S. where soils are usually “older” from faster weathering in a hot, wet climate of more easily degraded parent materials and lower amounts of SOM. Lime and other soil amendments are frequently added to increase soil pH closer to neutral thereby increasing the availability of plant essential nutrients while decreasing the availability of toxic soil chemicals in the soil. However, these amendments still cannot replace the contribution of native CEC to that of plant nutrition and ultimately crop productivity, even in an aged soil.
Nearly the same time I was first learning about CEC in soils in college, I fell head over heels in love with one of my favorite verses of all time, 2 Corinthians 5:21 (GW) God had Christ, who was sinless, take our sin so that we might receive God’s approval through him. Today I still don’t understand CEC, much less this verse, to their fullest which makes me even more appreciative of this verse as the most glorious exchange ever! The exchange of my sin for his righteousness – literally, my waste for the essential righteousness imparted to me by Christ for today and forever is as mind-blowing a concept now as it was years ago!) Just as plants can’t provide nutrients for themselves for they are dependent on what they receive from the soil via CEC, I can’t gain righteousness except via the death, burial, resurrection of the sinless Christ as fully God and fully man. And Christ didn’t do this just for me, He did it for all who would receive him (see John 3:16-17). Only Christ could accomplish what no one else could achieve!
He did this once for all, once forever (see Romans 6:10 and Hebrews 10:10). Yet He gives me the privilege, the joy, the gift of remembering the waste of my sin in the full assurance that it has been exchanged for salvation by grace through faith (Ephesians 2:8). A most magnificent exchange! This exchange alone would be far more than I could ever ask or imagine as per Ephesians 3:21, but the exchanges don’t stop there…
Creator God provides daily for my needs in a myriad of ways just as He does for the sparrows and the lilies (see Matthew 6:28). He gives fullness, abundance, and grace in all ways to my life in Him (see Colossians 2:10). He alone provides those essentials that I might not even realize (or often overlook) as needed for daily life and growth – such things as beauty for ashes, gladness for mourning, praise for weakness (Isaiah 61:3); dancing for mourning, gladness for weeping (Psalm 30:11); compassion and caring for anxious thoughts (1 Peter 5:7); and other marvelous exchanges. He alone is capable of all of these exchanges if I will but come to Him as in Matthew 11:28-30 Come to me, all who labor and are heavy laden, and I will give you rest. Take my yoke upon you and learn from me, for I am gentle and lowly in heart, and you will find rest for your souls. For my yoke is easy, and my burden is light.
The truth of this exchange of my agenda for His plan is often not what I like or even think best. Yet when I do finally humble myself and come to Him for this exchange, He always provides that quietness of soul rest that I can’t obtain anywhere else. And only this true soul rest gives the peace that passes all understanding able to guard my heart and mind from all the chaos trying to take me over (Philippians 4:7). In turn, this peace helps me hear that Jesus daily calls me to the life-giving exchanges of apathy for love, humility for pride, longsuffering for impatience, forgiveness for bitterness, trust for worry, judgment for mercy, truth for lies, rest for striving, eternity for now. Often, I don’t like these exchanges but they are necessary for growth, both for me and for others in my world, especially those who haven’t found my magnificent Jesus for themselves yet.
Jesus knows exactly where these people are and gives me opportunity to respond to them with the love, humility, longsuffering, and such He has given me. It’s definitely not easy to respond as Jesus would to those whose choices, words, and/or responses are increasing the acidity in my stomach and unrest in my heart as they try to weather away the peace I’ve found in Christ. Yet Jesus reminds me that He dearly loves them (and me) and that I can’t create the peace; I can only receive it in exchange for my arrogance. Only Jesus is strong enough to buffer my reactions of anger into responses of obedience and slowly, patiently changing my heart to be more like His. For when my heart becomes more and more like His, it can be that adamah (“fertile soil”) for His purposes and His people. And then I can pray and respond in love to those who desperately need to know His love and His peace for now and forever.