The Conservationist

Last August 13, 2008, I happened to be invited through our office by the Security and Escort Battalio, HHSG, PA at Fort Bonifacio, Metro Manila.  The intention is to lecture on proper use of fertilizer and  procedures on Agricultural Production and train some of their personnel to carry out the said endeavor.  It’s always a good opportunity for us working at the Department of Agriculture (DA) because through this kind of activity, we can continuously educate people on other field of discipline at the same time promote the DA program.

I prepared a lecture on Integrated Nutrient Management (INM) believing that INM is a wholistic approach that they can use in Agricultural Prodeuction.  INM is a means of utilizing all the available fertilizer source inside and outside of the farm at the same time integrating available technologies. I started my lecture with the objectives of INM: I emphasized  to them that with INM, we can sustainably manage our farm land; maintain the quality of the soil (physical, biological and chemical properties); promote a low cost management; and use envornmental friendly technologies.

In the use of INM, there are things to be considered:

• Technical applicability – that means asking ourselves whether we can just use manure or organic pertilizer?  Can we avoid the use of inorganic fertilizer? Or do we need a combination?  Will the nutrients from organic fertilizer be enough to sustain the needs of the plant and attain the yield we target?
• Economic returns -  among the many available means of producing good crop, which is the most economical and affordable to the farmer, at the same time good for the environment as a whole not only for the soil.
• Practical fesibility – if ever the farmer decided to use a technology, say for example, organic fertilizer, do they have the capability to mix 10T of organic fertilizer or can they source out this volume in the farm or will enough labor force be available?
• Social acceptability – it’s always good to check on the social acceptability of the technology.  We need to look at the effect on the enviroment (water, soil and air).

I went to explain to them that if ever they are decided to use the INM as technology, it’s always good to start to know whether the soil has enough nutrients to support plant growth or do they need to apply additional input, if ever what to apply and by how much.   There are means to do that:

• Soil Analysis - this is done by simply taking soil samples and analysing it. It will give us the indication of the sufficiency and deficiency of a particular element, and what need to apply and by how much.
• Plant Tissue Analysis – this method complements the soil tissue analysis, instead of getting soil sample part of the plant is the one being analyse.  With proper procedure, plant tissue analysis could give a good indication of nutrient sufficiency and deficiency.
• Field Experiment or Biological Test – setting up a simple experiment, for example what  volume of crop residues can significantly increase yield; what combination of inorganic fertilizer; time of application and so on.  This is always a good practice to do before adoption of any technology.  We can start with small lot in the farm, then test the technology if it will work or not.  Say the use of earthworm cast.  We can apply this in a portion of the farm and then compare the effect on those without application.  Farmer will have a first hand experience and at the same time familiarize themselves on the technology.
• Visual Diagnosis of Observing Difficiency Symptoms – this is done by daily observation of the crop stand, observing the plant of color abnormality or appearance like yellowing (defficent in nitrogen) , purpose color (defficent in phosphorus, scorching (defficient in K), stunted growth (N), curling of the leaves (Ca) , white strips (Mg) and others.  By careful observation of deviation from the normal plant will give an indication of what particular element is defficient. There are some difficulty regarding the method because defficiency could be a combination of particular element. Further, defficiency could appear at the late stage and providing the necessary measure is a bit late.

Aside from what mentioned above, defficency of particular element can be assessed through general soil fertility evaluation.  This can be done by answering questions such as: time of fertilizer application; is there enough moisture when fertilizers were applied; right kind of fertilizers were applied; right amount of fertilizers were applied; were fertilizers thoroughly mixed to the soil; used balanced fertilization; organic fertilizers were used and so on.

Then I provided them some options of managing the natural resources such as: recycling; nutrient budgetting; use of organic fertilizers (i.e. compost; liquid manures); use of crop rotation; use of conservation tillage; use of cover crop and proper intercropping; good cropping pattern; use of leguminous crop in the cropping pattern and others.

I also discussed several means in maintaining the fertility of the soil and minimize depletion at the same time maintaining the good soil quality: planting crops that are suitable to the inherent characteristics of the soil; minor alteration of the soil inerent fertility level through the use of organic fertilizer; and use of balanced fertilization.

I also mentioned a little on soil erosion and many other things which I will discuss in details in my next writting.

A cover crop can be sown between cropping operations or as a companion crop during the early stages of crop development. An example of a cover crop system used in the Philippines is sowing mungbean with maize. The mungbean are either sowed at the same time with maize as intercrop or as relay cropping or a crop after maize (crop rotation). There is however some difficulties in the use of cover crops. One is competition for soil moisture and sunlight with the cash crop.

Maintaining ground cover either as an intercrop, relay, or crop in rotation is critical in reducing the effects of raindrop impact and soil aggregate disintegration. Ground cover prevents raindrops from directly striking the soil surface and allows rainfall to slowly penetrate the soil surface. Thus, reducing the amount of rainfall that goes to runoff and make more water available for plant growth.

There are a number of options to maintain vegetation or cover during and between cropping operations. One is stubble’s retention; retaining surface stubble provides ground cover and organic matter during fallow periods and successive crops. Advantages of stubble include no competition with the crop in terms of moisture and reduced herbicide use. However, there could be some difficulties in sowing seeds directly to the crop stubble’s specially ion thick-stubbles. These difficulties with tillage and sowing through the stubble may be overcome by finely chopping the stubble before sowing and modifying direct drilling equipment.

As a Conservation man working on Soil Fertility maintainance and rehabilatation, we want to share our new experience in terms of cover crop.  Right now through the JIRCAS Project, we are working on Conservation tillage (Minimum  or Zero Tillage) in Ilagan, Isabela.  We are trying to validate the effects of conservation tillage and  conventional tillage (intensive plowing and harrowing) in sloping areas planted to corn.  We are also testing cover crops that will not only protect the soil from the effect of heavy rainfall but at the same time will produce enough biomass that can be used as mulch and later on will decompose and add organic matter to the soil.

In this project, initially, we tried mungbean as inter crop to corn.  We intend to use this as soil cover during the time that corn as the main crop is not growing in the field.  Mostly, this time is during the turn over period after harvest of the May to September crop and before the start of October to February crop.  We want that because after corn harvest in September, it leaves the soil bare and prune to erosion because during the month of September and October,  we always experience heavy down pour.

Results of our work suggest that mungbean is a good crop that can add income to the farmer as it can produce pods and a very good source of protein.  However, as cover crop, it cannot serve our purpose of protecting the soil during the turnover period.  It has very short life cycle and usually harvested earlier than the main crop.

Realizing that mungbean will not serve the purpose, we tried pigeon pea.  In the very first cropping that we have, we noticed that pigeon pea is a good dry land crop.  We planted pigeon pea in the farmers field during the month of February and it survived even without watering (February, March and April are dry months in Ilagan, Isabela) until the month of May, where we experienced the first rain.  Pigeon pea can produce heavy biomass that can be used as mulch and add soil organic matter.  During the the first two months of corn, pigeon pea should be pruned twice a month or else it will out grow the corn.  Then, even if you cut the pigeon pea on the first node of branching, it recovers very past.  It has also very good root system.  Root development can extend as much as 70 cm deep even if the plant is maintained by cutting at about knee high.  The deep root penetration is very important in recycling nutrient from the deep horizon back to the surface.

When we harvested the corn, and allow pigeon pea to re-grow, it continuously bear flower and initiate podding.  This is very good for the farmers.  Since pigeon pea is producing so much biomass, mulch to protect the soil is ensured.  Weed growth is also suppressed. Additionally, because pigeon pea is producing heavy biomass, increase in soil organic matter content is remarkable.

Pigeon pea is also a good feed for the livestock.  In one of our site (SWMS), they are growing goat, and these animals love to eat pruned leaves of pigeon pea.  Care takers of these animals are now inquiring us where can they source pigeon pea seeds.  If possible, they want to try growing pigeon pea and feed the leaves on their livestock.  Farmers in the vicinity of our project in San Antonio, Ilagan, Isabela are beginning to notice the beauty of pigeon pea.  In fact, they are now starting to ask how can they source seeds and plant in the area.

We have just started using pigeon pea as cover crop, initial results are very promising.  We will continue to work on it…

Pigeon pea used as cover crop (JIRCAS-BSWM Project; Ilagan, Isabela; 2008)