Ap­ple nu­tri­tion in Hi­machal Pradesh

An ar­ti­cle in May looked at the Hi­machal Pradesh ap­ple in­dus­try in north­ern In­dia, and the World Bank pro­ject to help in­crease ap­ple, pear and sub­trop­i­cal pro­duc­tiv­ity. This ar­ti­cle looks at nu­tri­ent man­age­ment prac­tices used there.

The Orchardist - - News - By Mike Nel­son

Plant & Food Re­search have been en­gaged for three years to sup­ply ex­perts along with Fruition Hor­ti­cul­ture, Ag­First En­gi­neer­ing and Ap­plied Re­search and Tech­nolo­gies. The team pro­vides train­ing and ad­vice around or­chard man­age­ment prac­tices and plant pro­tec­tion meth­ods.

His­tor­i­cally Red de­li­cious is the main cul­ti­var grown on seedling root­socks. The in­dus­try grows about 40 mil­lion car­tons with av­er­age pro­duc­tion of six tonnes per hectare in­volv­ing more than 100,000 grow­ers, many who are very small scale with only about 50 trees. So giv­ing a value per hectare has lit­tle mean­ing, with rates of fer­tiliser given as a rate per tree.

There are few flat ar­eas in the state so most plant­ings are on ter­races on steep hill­sides. Rows are of­ten curved which makes con­struc­tion of any sup­port struc­ture dif­fi­cult. There is now a push to in­tro­duce new cul­ti­vars on clonal root­stocks and the use of drip ir­ri­ga­tion. Vir­tu­ally all pro­duc­tion is mar­keted do­mes­ti­cally.

Look­ing at this in­dus­try gives a good in­sight to where New Zealand grow­ers have come from in their nu­tri­ent man­age­ment prac­tices. It also high­lights the rea­sons why we do what we do, such as timely trace el­e­ment ap­pli­ca­tions and fo­liar sprays, and track­ing of soil and fo­liage nu­tri­ent lev­els. Soil test­ing has not been a com­mon in most or­chards in Hi­machal Pradesh, but the pro­ject has funded and pro­moted a large in­crease in the num­ber of blocks tested. In one re­gion where 70 blocks were tested there was a wide vari­a­tion in soil pH. More than half the blocks tested had a pH that was out of the op­ti­mum range of 5.8 to 6.8. With 24 per­cent of blocks be­low the op­ti­mum pH of 5.8 and a sur­pris­ing 31 per­cent of blocks above the op­ti­mum pH of 6.8, there were 16 blocks of the 70 above a pH of 7.2.

This gives a huge op­por­tu­nity for im­prov­ing their per­for­mance. Main­tain­ing cor­rect soil pH en­sures that there’s op­ti­mum nu­tri­ent avail­abil­ity and soil bi­o­log­i­cal ac­tiv­ity. Low pH can make some nu­tri­ents such as man­ganese and alu­minium highly

sol­u­ble lead­ing to toxic lev­els in the plant and con­versely too high a pH can make some nu­tri­ents in­sol­u­ble and be­come de­fi­cient. Highly sol­u­ble man­ganese can re­sult in tox­i­c­ity symp­toms such as ‘bark measles’.

Even in NZ, while there is a good un­der­stand­ing of raising a low pH with lime, grow­ers are less con­scious of the po­ten­tial problems of higher pHs. At a pH of 7, man­ganese is be­com­ing in­sol­u­ble and un­avail­able, along with zinc, cop­per and iron. At 7.2 it’s vir­tu­ally in­sol­u­ble (see Fig­ure 1) re­sult­ing in leaf de­fi­ciency symp­toms of pale in­ter­veinal ar­eas. Symp­toms are sim­i­lar to mag­ne­sium de­fi­ciency ex­cept the fine leaf veins tend to re­main green.

While leaf test­ing may show low plant man­ganese lev­els, and the re­sponse would be to ap­ply a fo­liar spray with man­ganese, the un­der­ly­ing cause is high pH, which should be eased back. We oc­ca­sion­ally see this prob­lem in NZ and this high­lights the fact that the first stage of good nu­tri­ent man­age­ment is main­tain­ing a cor­rect soil pH.

Of course, with nu­tri­ents and fer­tiliser, ev­ery­one would like it to be as sim­ple as pos­si­ble, and Hi­machal Pradesh, with many small hold­ings, is no ex­cep­tion. They have de­vel­oped a sys­tem of pre­scrib­ing fer­tiliser based on tree age. For an es­tab­lished six-year-old high den­sity plant­ing the rec­om­men­da­tion is 210 grams per square me­tres of urea, 300 gm/m2 of su­per phos­phate and 210 gm/m2 of potas­sium chlo­ride.

The ap­pli­ca­tion area un­der trees is called the tree basin which tends to be a cir­cu­lar, cul­ti­vated area around the tree, of­ten with mound­ing around the perime­ter to con­tain wa­ter, a bit like a minia­ture border dyke style of ir­ri­ga­tion. This equates to very high rates of N P K. For ni­tro­gen this would be in the range 230kg N/ha com­pared with about 50 - 70kg N/ha ap­plied in NZ. For phos­phate ap­prox­i­mately 65 kg/ha is rec­om­mended com­pared with 10 - 20 kg/ha ap­plied as main­te­nance dress­ings in NZ. The amount of potas­sium ap­plied is rel­a­tively high as well at 250 kg K/ha. These val­ues may be ap­pro­pri­ate when build­ing fer­til­ity but ap­plied con­tin­u­ally are likely to be ex­cess to plant re­quire­ments, par­tic­u­larly ni­tro­gen, and detri­men­tal to good fruit set, fruit colour and qual­ity.

Fer­tiliser is not the only nu­tri­ent source. Many of the or­chards are part of a mixed farm with an­i­mals and other crops sup­ply­ing a ready source of com­posted an­i­mal ma­nure which is ap­plied, at any­thing up to 5 kg/m2 as a mulch and slow re­lease nu­tri­ent source. While this is very good for soil health, min­er­al­i­sa­tion of nu­tri­ents, par­tic­u­larly ni­tro­gen, is likely to be high late in the sea­son when it’s warm and the mon­soon weather is con­tribut­ing am­ple soil mois­ture. This is a pe­riod when we would like to see lim­ited avail­abil­ity of ni­tro­gen, to as­sist with fruit colour de­vel­op­ment and qual­ity.

Boron de­fi­ciency was seen on some or­chards. Fruit symp­toms are seen early in the sea­son with dark pit­ting, pro­gress­ing through to cracks and de­formed fruit. This should not be con­fused with bit­ter pit, caused by lack of cal­cium, which is seen late in the sea­son. This de­fi­ciency can eas­ily be avoided with fo­liar boron ap­pli­ca­tions pre-flow­er­ing and soil ap­pli­ca­tions.

Also of in­ter­est is the wide­spread use of potas­sium chlo­ride. We use the sul­phate form of potas­sium, as potas­sium chlo­ride is con­sid­ered risky with many hor­ti­cul­tural crops due to the risk of chlo­ride tox­i­c­ity. How­ever, I have yet to see any signs of chlo­ride tox­i­c­ity even at higher rates used.

As this in­dus­try moves to newer cul­ti­vars nu­tri­ent man­age­ment will be be­come even more im­por­tant. Grow­ers and ad­vi­sors will gain a bet­ter un­der­stand­ing of soil and tis­sue test­ing, and plant ob­ser­va­tion to make bet­ter nu­tri­ent de­ci­sions rather than us­ing a one-size-fits-all ap­proach.

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