How to properly handle manure for optimum crop yield

Des­pite its dis­cov­ery by farm­ers all over the world since an­cient days in its con­nec­tion with in­creased crop pro­duc­tion, farm­ers in Africa es­pe­cially Sub-Saha­ran Africa (SSA) do not apply re­com­men­ded ma­nure man­age­ment prac­tices in their farm­ing lead­ing to poor yields.

Ac­cord­ing to May this year re­search in 13 SSA coun­tries by a team of ex­perts on Ma­nure Man­age­ment Prac­tices and Policies in Sub-Saha­ran Africa: Im­plic­a­tions on Ma­nure Qual­ity as a Fer­til­izer, ef­fect­ive use of live­stock ma­nure as a fer­til­izer de­pends crit­ic­ally on meth­ods of ma­nure hand­ling and stor­age which most small­holder farm­ers in the con­tin­ent may not be aware of.

In Kenya, for in­stance, the gov­ern­ment the gov­ern­ment this year pro­posed a new bill through the Food Crops Reg­u­la­tions 2018 which if passed was to make it il­legal for farm­ers to use an­imal ma­nure in food pro­duc­tion.

The reg­u­la­tion 30 (1) and (2) of the bill which was draf­ted by the Cab­inet Sec­ret­ary Ag­ri­cul­ture, county gov­ern­ments and the Ag­ri­cul­ture and Food Au­thor­ity states that a grower shall not use raw an­imal ma­nure for the pro­duc­tion of food crops. In­stead, grow­ers shall only use chem­ical fer­til­izers at rates re­com­men­ded by the re­spect­ive County Gov­ern­ment.

“This was in­formed by the fact that most of our farm­ers are not ad­her­ing to good ag­ri­cul­tural prac­tices es­pe­cially in hand­ling the ma­nure hence af­fect­ing our ex­port mar­ket as the fresh pro­duce may fail health test by the Glob­al­GAP,” said Ant­ony J.N. Nyaga, KALRO – PTC.

Due to pub­lic health con­cerns, the Glob­al­GAP for­bids the ap­plic­a­tion of un­treated ma­nure on leafy ve­get­ables once they are planted and re­stricts ma­nure ap­plic­a­tion to 60 days be­fore har­vest­ing for other crops.

In ad­di­tion, poorly dis­charged ma­nure can lead to con­tam­in­a­tion and eu­troph­ic­a­tion of sur­face and ground­wa­ter mainly with ni­trate.

Some of these basic re­com­men­ded ma­nure man­age­ment prac­tices in­clude roof­ing an­imal hous­ing, hav­ing a wa­ter-proof floor or cov­er­ing ma­nure dur­ing stor­age.

Without the prac­tices farm­ers risk caus­ing large nu­tri­ent losses dur­ing ma­nure stor­age, in­creas­ing green­house gas emis­sions, and re­du­cing the qual­ity of the ma­nure as a fer­til­izer.

RE­LATED ART­ICLE: For­ti­fied com­pos­ite ma­nure in­creases har­vest two-fold

In a sur­vey of ma­nure man­age­ment prac­tices on small, me­dium, and large scale farms in Ethiopia and Malawi in­dic­ated that farm­ers lack know­ledge on ma­nure man­age­ment.

However, farm­ers are able to ac­cess ag­ri­cul­tural ex­ten­sion ser­vices from both gov­ern­ment and non-gov­ern­ment agen­cies, al­though these ex­ten­sion ser­vices rarely in­cluded in­form­a­tion on im­proved ma­nure man­age­ment prac­tices.

Ma­nure con­tains im­port­ant plant nu­tri­ents such as ni­tro­gen (N), phos­phorus (P), po­tassium (K), and other sec­ond­ary nu­tri­ents and trace ele­ments that if well-man­aged it can be an asset, pro­mot­ing sus­tain­able ag­ri­cul­ture, and in­creas­ing crop pro­duc­tion and mar­ket­ab­il­ity of the pro­duce, par­tic­u­larly for small­holder farm­ers in sub-Saha­ran Africa (SSA).

RE­LATED ART­ICLE: Nyamira farmer look­ing for ma­nure sup­pli­ers in Kisii, Bomet, Kericho and Homa Bay

Ma­nure Col­lec­tion

Col­lect­ing a mix­ture of bed­ding ma­ter­ial, feed waste, flush­ing water, feath­ers, and soil among oth­ers to­gether with an­imal ex­creta af­fects the nu­tri­ent con­tent of the live­stock ma­nure.

This is be­cause bed­ding ma­ter­i­als such as straws usu­ally have lower N con­cen­tra­tion than the an­imal ex­creta.

RE­LATED ART­ICLE: Why the pro­posed an­imal ma­nure bill could hurt Kenya’s food pro­duc­tion goals

Ma­nure Treat­ment

Treat­ing or cur­ing ma­nure can be done in sev­eral ways such as dry­ing and com­post­ing. The lat­ter is ad­vant­age­ous to the ma­nure user be­cause it re­duces the bulk, however, it can res­ults into high losses of nu­tri­ents es­pe­cially ni­tro­gen hence in­dir­ect dry­ing in sun­light is re­com­men­ded.

Com­post­ing is an at­tract­ive op­tion for turn­ing on-farm or­ganic waste ma­ter­i­als into a valu­able farm re­source which is an ex­cel­lent soil im­prover and is cheaper than other soil amend­ments.

By provid­ing or­ganic mat­ter and soil nu­tri­ents, com­post im­proves the struc­ture of the soil, al­low­ing for bet­ter aer­a­tion, im­prov­ing drain­age, nu­tri­ent and water re­ten­tion, and re­duced risk of erosion.

RE­LATED ART­ICLE: Com­bin­ing ma­nure and fer­til­izer doubles crop yields

Ma­nure Stor­age

Stored ma­nure should be covered well to pre­serve the nu­tri­ents and help speed up de­com­pos­i­tion of the raw ma­nure.

Here a plastic film is re­com­men­ded. This is be­cause it can only let 20 per cent of ni­tro­gen out as com­pared to 55 per cent ni­tro­gen loss in ma­nure that is stored in open heaps.

An­other study in West­ern Kenya also has found that ma­nure stored in open pits had lower mass frac­tions of N and P than ma­nure in heaps under roof and in open heaps.

It is there­fore re­com­men­ded to shade ma­nure stor­age fa­cil­it­ies as much as pos­sible in order to re­duce ex­pos­ure to high tem­per­at­ures and sub­sequent N losses, as well as lim­it­ing ex­pos­ure to rain­fall, and thus min­im­iz­ing nu­tri­ent losses due to leach­ing

RE­LATED ART­ICLE: Farm using goat ma­nure as mulch and fer­til­iser doub­ling its pro­duc­tion

Ma­nure Ap­plic­a­tion

Most farm­ers in SSA apply ma­nure in ag­ri­cul­tural fields in holes, in fur­rows or spread/broad­cas­ted and in­cor­por­ated.

However, it is re­com­men­ded that the ma­nure be in­cor­por­ated into the soil im­me­di­ately after ap­plic­a­tion, as it will re­tain more nu­tri­ents (in par­tic­u­lar N) that will later be avail­able to crops.

For ex­ample, 90% of N from li­quid ma­nure will be avail­able to plants if it is in­cor­por­ated within 8 h com­pared to only 40% N avail­ab­il­ity if in­cor­por­a­tion is done after 5–7 days.