The mer­its and pit­falls of bi­o­log­i­cal farm­ing

Bi­o­log­i­cal farm­ing is a catch­phrase that is bandied about by some fringe fer­tiliser com­pa­nies and con­sul­tants.

NZ Grower - - Agronomist - Robin Boom /

They of­ten rad­i­cally re­duce the in­puts of con­ven­tional NPK fer­tiliser prod­ucts and in­tro­duce ideas and prod­ucts that sup­pos­edly en­hance soil bi­ol­ogy (earth­worms and micro­organ­isms) and im­prove the nu­tri­ent value of plants. Im­proved plant and fruit brix lev­els, lower weed and pest in­fes­ta­tion, a less­ened de­pen­dence on chem­i­cal sprays and build­ing up of soil car­bon lev­els are also claimed.

Bi­o­log­i­cal farm­ing dif­fers from or­ganic farm­ing, as grow­ers can still use chem­i­cal sprays when needed, and some of the fer­tilis­ers used are ar­ti­fi­cially man­u­fac­tured, whereas un­der or­ganic farm­ing, only reg­is­tered nat­u­rally oc­cur­ing prod­ucts such as re­ac­tive phos­phate rock (RPR), ele­men­tal sul­phur, potas­sium chlo­ride, an­i­mal ma­nures and com­posts that meet cer­tain stan­dards can be used. Con­ven­tional syn­thetic chem­i­cal sprays are a no-no.

On the face of it bi­o­log­i­cal farm­ing sounds too good to be true and it’s un­der­stand­able that farm­ers and grow­ers are tempted to look at what these fringe com­pa­nies are pro­mot­ing.

Bi­o­log­i­cal fer­tiliser com­pa­nies take their lead from overseas ‘ex­perts’ who have come to New Zealand pro­mot­ing their ideas through sem­i­nars and work­shops, such as Amer­i­can, Ar­den Anderson, who is au­thor of a num­ber of books re­lated to agri­cul­ture and also is a prac­ti­tioner of al­ter­na­tive hu­man medicine. Ex­pat Kiwi mu­si­cian Graeme Sait, has set up a suc­cess­ful busi­ness called Nu­tri-Tech So­lu­tions across the Tas­man in Queens­land and has also writ­ten sev­eral books, again over­lap­ping agri­cul­ture and hu­man nu­tri­tion.

And Amer­i­can agron­o­mist, Neil Kin­sey, is the au­thor of the book Hands on Agron­omy. Kin­sey’s ap­proach to soil fer­til­ity rigidly em­braces the ideas of Dr Wil­liam Al­brecht who in the 1930s 40s and 50s re­searched the dele­te­ri­ous ef­fects of high NPK fer­tilis­ers on the up­take of other el­e­ments, and their neg­a­tive ef­fect on plant, an­i­mal and hu­man health. Along with fel­low re­searchers Drs Bear and Toth they came up with an ideal ra­tio of ma­jor cations cal­cium, mag­ne­sium, potas­sium and sodium, sug­gest­ing they should make up 68 per­cent, 10-12 per­cent, three to five per­cent and one to two per­cent re­spec­tively of the base

On the face of it bi­o­log­i­cal farm­ing sounds too good to be true and it's un­der­stand­able that farm­ers and grow­ers are tempted to look at what these fringe com­pa­nies are pro­mot­ing.

sat­u­ra­tion per­cent­ages from soil tests.

This base sat­u­ra­tion ra­tio (BSR) ap­proach to soil test­ing for crop nu­tri­ent lev­els was later tri­alled in the United States against the stan­dard suf­fi­ciency level of avail­able nu­tri­ents (SLAN) ap­proach us­ing parts per mil­lion (ppm) of nu­tri­ent lev­els (Min­istry for Pri­mary In­dus­tries’ Quick Tests are based on this), and it was found the SLAN ap­proach was a bet­ter pre­dic­tor of crop re­sponses.

Anderson is a critic of the most com­mon fer­tilis­ers we use here such as urea, di­a­mo­nium phos­phate (DAP), su­per­phos­phate and muri­ate of potash (potas­sium chlo­ride), claim­ing the lat­ter in par­tic­u­lar was the worst pos­si­ble fer­tiliser for soils. This is all music to much of the al­ter­na­tive fer­tiliser in­dus­try who seize on the sup­posed harm caused by con­ven­tional fer­tilis­ers, sell­ing their brands of bi­o­log­i­cal fer­tiliser prod­ucts or blends which, when an­a­lysed on their nu­tri­ent value, are of­ten highly

in­flated in price com­pared with an equiv­a­lent blend from one of the two ma­jor fer­tiliser com­pa­nies, Bal­lance or Ravens­down.

A com­mon fea­ture of these bi­o­log­i­cal farm­ing sales­peo­ple is that they gen­er­ally lack any for­mal qual­i­fi­ca­tion in agri­cul­tural sci­ence and are dis­mis­sive of his­tor­i­cal sci­en­tific re­search done in NZ or are very se­lec­tive in any re­search they do quote.

In the NZ Jour­nal of Ex­per­i­men­tal Agri­cul­ture 1987, Vol 15, there was a pa­per in­ves­ti­gat­ing the ef­fec­tive­ness of a com­mer­cially avail­able en­zyme-based soil con­di­tioner on sports turf at Tonga Park and Caris­brook. The re­searchers re­ported:

“The claims made for the ef­fects of the con­di­tioner are impressive. If proven ef­fec­tive in ‘ac­ti­vat­ing soil bac­te­rial ac­tiv­ity’ and ‘in­creas­ing deep wa­ter pen­e­tra­tion’, this prod­uct would in­deed be a valu­able tool for sports ground man­age­ment as well as in agri­cul­ture gen­er­ally. This trial has tested the ef­fi­cacy of the con­di­tioner us­ing a wide range of soil chem­i­cal, bi­o­log­i­cal/bio­chem­i­cal and phys­i­cal cri­te­ria and found no ev­i­dence to sup­port these claims. There was no visual field ev­i­dence of any re­sponse to the con­di­tioner… Our re­sults sup­port those of pre­vi­ous stud­ies.”

In a crit­i­cal re­view of the value to agri­cul­ture of mi­cro­bial fer­tilis­ers, ac­ti­va­tors, and con­di­tion­ers, Duigan (1979) re­ferred to them as “mirac­u­lous cure-alls” for any soil or crop prob­lem, and stated that ‘their mode of ac­tion was usu­ally shrouded in mys­tery.He found no repli­cated test data to sup­port man­u­fac­tur­ers’ claims.

Duigan’s com­ments can prob­a­bly be echoed when we con­sider the cur­rent fer­tiliser scene in NZ where so-called fringe fer­tiliser com­pa­nies sell their prod­ucts whose “mode of ac­tion is usu­ally shrouded in mys­tery”. The fer­tiliser in­dus­try is still a buyer-be­ware in­dus­try and there are many mil­lions of dol­lars wasted each year on use­less or ex­pen­sive prod­ucts.

Most of the bi­o­log­i­cal farm­ing phi­los­o­phy in­volves us­ing some form of lime (cal­cium), phos­phate in very small quan­ti­ties if at all, trace el­e­ments and sup­posed bi­o­log­i­cal stim­u­lants such as hu­mus, ful­vic acid, sugar, mo­lasses, com­post teas, sil­i­con, com­post, rock dust, ze­o­lite, pro­bi­otic en­zymes and spe­cific strains of bac­te­ria or fungi. From what I have ob­served, it is usu­ally the lime or trace el­e­ment com­po­nent in bi­o­log­i­cal mixes that gives a re­sponse, as it is these that nu­tri­ents the main­stream fer­tiliser com­pa­nies have not his­tor­i­cally pro­moted as be­ing that im­por­tant. Lime and trace el­e­ments are vi­tally im­por­tant, but so too are the ma­jor el­e­ments ni­tro­gen, phos­pho­rous, potas­sium and sul­phur, and these need to be ap­plied in the most cost ef­fec­tive way, sourced from which­ever com­pany is the cheap­est. Bi­o­log­i­cal re­sponses are very un­pre­dictable and can be quite sig­nif­i­cant, but bi­ol­ogy still needs the nu­tri­ent base in the soil to work with.

Hav­ing good drainage and soil struc­ture (plenty of oxy­gen), good or­ganic mat­ter (hu­mus) lev­els, a good soil pH and good lev­els of all 16 of the es­sen­tial macro and mi­cronu­tri­ents should give soil biota the best chance to work any magic.

CPAg, Mem­ber of the In­sti­tute of Pro­fes­sional Soil Sci­en­tists

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