Good habits to be cul­ti­vated

Matamata Chronicle - - Rural Delivery - By BALA TIKKISETTY

Us­ing good cul­ti­va­tion prac­tices helps farm­ers pro­tect both the fi­nan­cial and en­vi­ron­men­tal bot­tom lines of their prop­er­ties.

Post-win­ter is the time when farm­ers are cul­ti­vat­ing their pad­docks to en­sure they can best pro­vide fresh pas­ture or the next crop.

Also, so-called ‘‘sac­ri­fice pad­docks’’ are nor­mally cul­ti­vated about now and sown with a sum­mer crop to re­store dam­aged soil.

As farm­ers go about this work, there are a num­ber of fac­tors to bear in mind to max­imise farm ef­fi­ciency and min­imise their en­vi­ron­men­tal foot­print.

Sed­i­ment and nu­tri­ents from farm­ing op­er­a­tions, along with ero­sion gen­er­ally, are some of the im­por­tant causes of re­duced water qual­ity in our re­gion.

Although much of the Waikato’s 2.5 mil­lion hectares is rel­a­tively sta­ble, the na­tional land re­sources in­ven­tory has iden­ti­fied more than 1 mil­lion ha af­fected to some de­gree by ero­sion, with ero­sion on al­most 36,000ha ranked as se­vere to ex­treme. A fur­ther 400,000ha is clas­si­fied as hav­ing se­vere ero­sion po­ten­tial.

Top soil ero­sion, es­pe­cially in hill coun­try, of bare or cul­ti­vated land, leads to the loss of valu­able nu­tri­ents.

It can also dis­rupt in­fra­struc­ture and in­creases the costs of main­te­nance ac­tiv­ity, such as clean­ing cul­verts and drains.

The great­est risk can be at times like now when the pro­tec­tive plant cover is lost through cul­ti­va­tion of soils for pas­ture re­newal and crop es­tab­lish­ment.

Even with well-es­tab­lished shel­ter­belts pro­tect­ing pad­docks, wind ero­sion can still oc­cur be­cause of in­ap­pro­pri­ate cul­ti­va­tion tech­niques.

Farm­ers with lighter soils should con­sider ‘‘con­ser­va­tion cul­ti­va­tion’’ mea­sures.

Th­ese are cul­ti­va­tion prac­tices aimed at main­tain­ing max­i­mum veg­e­ta­tive cover on the soil sur­face and which en­cour­age mois­ture re­ten­tion in soils. The aim is to pro­duce an un­even soil sur­face in as ‘‘rough’’ a con­di­tion as prac­ti­ca­ble and to re­strict the cul­ti­va­tion pe­riod to the min­i­mum time.

The use of the chisel plough or grub­bers is rec­om­mended as th­ese give a fine deep seedbed while still re­tain­ing a cloddy sur­face. Top­work­ing im­ple­ments, disc­ing and rolling can cre­ate a fine seedbed prone to ero­sion even in well­shel­tered sit­u­a­tions.

Con­tour cul­ti­va­tion, sow­ing at right an­gles to the pre­vail­ing wind, sed­i­ment re­ten­tion, and re­duc­ing runoff are rec­om­mended for min­imis­ing soil loss.

Soils should be cul­ti­vated when the mois­ture con­tent is nei­ther too high nor too low.

To as­sess if soils are suit­able for pri­mary cul­ti­va­tion, take a piece of soil (half the vol­ume of an in­dex fin­ger) and press firmly to form a pen­cil.

Roll the soil into a ‘‘worm’’ on the palm of one hand with the fin­gers of the other un­til it is about 50 mm long and 4 mm thick.

Ex­ert suf­fi­cient pres­sure with your fin­gers to re­duce the di­am­e­ter of the worm to 4 mm in 15 to 20 com­plete for­ward and back move­ments of the fin­gers.

Con­di­tions are suit­able for cul­ti­va­tion if the soil cracks be­fore the worm is made.

The soil is too wet to cul­ti­vate if you can make the worm.

Clods that are too dry will not break down with cul­ti­va­tion to give a good seedbed.

Sat­is­fac­tory re­sults are achieved when cul­ti­va­tion is car­ried out at a suit­able soil mois­ture con­tent and at a suit­able depth.

If good pre­cau­tions are ob­served, a ’’two-pass cul­ti­va­tion’’ (ie two passes of cul­ti­va­tion equip­ment) is needed to pre­pare a seedbed.

Other con­ser­va­tion cul­ti­va­tion tech­niques in­clude the suite of prac­tices known as min­i­mum tillage or no tillage – the least cul­ti­va­tion pos­si­ble, or none at all, to re­duce soil dis­tur­bance.

If soil has been con­tin­u­ously cul­ti­vated for many years, the struc­ture is likely to be poor be­cause cul­ti­va­tion re­duces soil or­ganic mat­ter lev­els.

No-tillage will not re­pair the dam­age overnight but, with residue re­ten­tion, it will even­tu­ally.

Chem­i­cal spray­ing fol­lowed by di­rect drilling is an op­tion on light erod­able soils.

A range of ma­te­rial from ad­ja­cent land can con­tam­i­nate wa­ter­courses.

This can in­clude sed­i­ment, nu­tri­ents such as ni­tro­gen and phos­pho­rous, other chem­i­cals and mi­crobes.

Sed­i­ment and some nu­tri­ents, par­tic­u­larly phos­pho­rus, are car­ried to streams pri­mar­ily in the over­land flow of water.

Dis­solved nu­tri­ents such as ni­tro­gen and other ma­te­ri­als (in­clud­ing dis­solved or­ganic car­bon) can also move through the soil in un­der­ground flows and con­tam­i­nate wa­ter­courses.

The area be­side wa­ter­ways that forms the in­ter­face be­tween water and land is called the ri­par­ian mar­gin.

This area is a cru­cial buf­fer be­tween land use ac­tiv­i­ties and the nat­u­ral wa­ter­way.

An ef­fec­tive fil­ter strip should be es­tab­lished and main­tained where over­land water can en­ter water bod­ies. Healthy ri­par­ian veg­e­ta­tion in th­ese ar­eas should be main­tained to im­prove bank sta­bil­ity, re­duce ero­sion, in­crease water qual­ity, re­duce stock losses, fil­ter sur­face run-off and to pro­vide habi­tat for wild life.

Suit­able ri­par­ian species fil­ter sed­i­ment, bac­te­ria and nu­tri­ents from sur­face runoff. Stud­ies show that up to 90 per cent of sed­i­ment can be caught in an ef­fec­tively con­structed fil­ter strip.

Any fae­cal bac­te­ria that are trapped in long grass fil­ter strips will die off in sun­light.

In the fil­ter strips, gen­er­ally, grasses should be kept to at least 10 to 15 cen­time­tres high with a good den­sity of stems and leaves at ground level for max­i­mum trap­ping ef­fect.

Ri­par­ian veg­e­ta­tion also has an im­por­tant ad­di­tional ben­e­fit in pro­vid­ing shade to the stream, thereby re­duc­ing water tem­per­a­tures and growth of nui­sance plants and al­gae as well as pro­vid­ing bank sta­bil­ity.

The Waikato Re­gional Coun­cil has a rule that farm­ers must not cul­ti­vate pad­docks within two me­tres of a river, stream or lake bed.

The fu­ture of farm­ing, on which our re­gion’s eco­nomic and so­cial well­be­ing re­lies heav­ily, could be at risk if the qual­ity and ex­tent of our soils are not main­tained.

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